UBC Theses and Dissertations

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UBC Theses and Dissertations

A recalibration of the Hγ luminosity relation with high signal-to-noise Reticon spectra Millward, Christopher Gordon 1983

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A RECALIBRATION OF WITH HIGH SIGNAL THE H 7 LUMINOSITY RELATION -TO-NOISE RETICON SPECTRA By CHRISTOPHER GORDON MILLWARD B . S c , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1979 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Dep a r t m e n t o f G e o p h y s i c s and Astronomy We a c c e p t t h i s t h e s i s a s c o n f o r m i n g to- t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA Ma r c h 1983 © C h r i s t o p h e r Gordon M i l l w a r d , 1983 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of Geophysics and Astronomy The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 D a t e April T?,, 19-83 DE-6 (3/81) i i ABSTRACT 40 A/mm h i g h s i g n a l - t o - n o i s e R e t i c o n s p e c t r a o f 71 O, B, and e a r l y A - t y p e s t a r s i n 8 open c l u s t e r s and OB a s s o c i a t i o n s a l o n g w i t h 37 z e r o p o i n t s t a r s ( e a r l y A - t y p e s t a r s w i t h r e l i a b l e t r i g o n o m e t r i c p a r a l l a x e s , e c l i p s i n g b i n a r i e s , and v i s u a l b i n a r i e s ) have been u s e d t o r e c a l i b r a t e t h e W ( H ? ) - a b s o l u t e m a g n i t u d e r e l a t i o n . The new e m p i r i c a l c a l i b r a t i o n f o r l u m i n o s i t y c l a s s e s I I I - V i s p r e s e n t e d . The c a l i b r a t i o n has a mean p r o b a b l e d i s p e r s i o n o f ± 0 .28 mag. No s p e c t r a l t y p e c o r r e c t i o n s a r e n e c e s s a r y . The new main s e q u e n c e c a l i b r a t i o n a v e r a g e s 0.1 mag. f a i n t e r t h a n t h e B a l o n a & Crampton (1974) c a l i b r a t i o n . C l o s e agreement w i t h t h e P e t r i e (1965) c a l i b r a t i o n i s f o u n d f o r s p e c t r a l t y p e s BO-7. However, t h e p r e s e n t r e l a t i o n i s up t o 0.8 mag. b r i g h t e r t h a n P e t r i e ' s 0 s t a r c a l i b r a t i o n and 0.7 mag. b r i g h t e r t h a n t h e A s t a r c a l i b r a t i o n . The Blaauw (1963) c a l i b r a t i o n a v e r a g e s 0.4 mag. f a i n t e r t h a n t h e p r e s e n t one o v e r t h e s p e c t r a l r a n g e 09-B2. The e f f e c t o f e v o l u t i o n and h i g h V s i n i on t h e r e l a t i o n a r e i n v e s t i g a t e d . The d e r i v e d d i s t a n c e modulus of NGC 2244, 11.00±0.27 mag., i s i n c l o s e agreement w i t h o t h e r d e t e r m i n e d v a l u e s and an e x p l a n a t i o n a s t o why P e t r i e o b t a i n e d an a n o m a l o u s l y low v a l u e (9.7±0.1 mag.) i s g i v e n . R o t a t i o n a l v e l o c i t i e s a r e d e t e r m i n e d f o r most s t a r s as w e l l as t h e c e n t r a l d e p t h s o f s e l e c t e d l i n e s . T a b l e o f C o n t e n t s A b s t r a c t i i T a b l e o f C o n t e n t s i i i L i s t of T a b l e s i v L i s t o f F i g u r e s v Acknowledgements v i i C h a p t e r 1. I n t r o d u c t i o n 1 C h a p t e r 2. The O b s e r v a t i o n s 12 C h a p t e r 3. D a t a R e d u c t i o n 32 C h a p t e r 4. The C a l i b r a t i o n 52 C h a p t e r 5. E v o l u t i o n a r y E f f e c t s 73 C h a p t e r 6. C o m p a r i s o n W i t h O t h e r C a l i b r a t i o n s 80 C h a p t e r 7. R o t a t i o n a l V e l o c i t i e s 91 C h a p t e r 8. S p e c t r a l T y p e s 95 C h a p t e r 9. C o n c l u s i o n s 100 B i b l i o g r a p h y 103 A p p e n d i x A 106 i L i s t of T a b l e s T a b l e I . Dates of O b s e r v a t i o n s 13 T a b l e I I . C l u s t e r and A s s o c i a t i o n Photometry 15 T a b l e I I I . C l u s t e r and A s s o c i a t i o n Data 22 Table IV. S t a n d a r d S t a r Data 29 T a b l e V. E q u i v a l e n t Width V a l u e s and A b s o u l u t e Magnitude.... 63 T a b l e V I . A b s o l u t e Magnitudes of MK S p e c t r a l Types. 64 T a b l e V I I . C l u s t e r and A s s o c i a t i o n D i s t a n c e M o d u l i 65 V . L i s t o f F i g u r e s F i g . 1. Av v s X4430 C e n t r a l D e p t h 17 F i g . 2. Sample S p e c t r u m 34 F i g . 3. Sample S p e c t r u m 35 F i g . 4. Sample S p e c t r u m 36 F i g . 5. Sample S p e c t r u m 37 F i g . 6. Sample S p e c t r u m 38 F i g . 7. Sample S p e c t r u m 39 F i g . 8. I n t e r n a l A c c u r a c y v s S/N o f S p e c t r a 41 F i g . 9. W ( H Y ) ( S t o c k ) v s W ( H 7 ) ( M i l l w a r d ) 43 F i g . 10. W ( H T ) ( B l a n c h a r d ) v s W ( H ? ) ( M i l l w a r d ) 44 F i g . 11. W(H7) ( B e e r ) v s W(H7) ( M i l l w a r d ) 45 F i g . 12. W(H7) ( P e t r i e ) v s Vl(Hy) ( M i l l w a r d ) 46 F i g . 13. W(H7) ( B a l o n a ) v s Vl(Hy) ( M i l l w a r d ) 47 F i g . 14. P l e i a d e s C l u s t e r Sequence L a t e r Than B7 50 F i g . 15. Mean R e s i d u a l s and D i s p e r s i o n v s S p e c t r a l Type ....55 F i g . 16. W(H7)-Vo C l u s t e r Sequence 56 F i g . 17. W(H7)-Mv f o r Z e r o P o i n t S t a r s 58 F i g . 18. F i n a l W(H7)-Mv C a l i b r a t i o n 61 F i g . 19. F i n a l W(H7)-Mv C a l i b r a t i o n 62 F i g . 20. C l u s t e r Member R e s i d u a l s v s W(H7) 67 F i g . 21. C l u s t e r and S t a n d a r d S t a r R e s i d u a l s v s W(H7) 67 F i g . 22. R e s i d u a l s v s S p e c t r a l Type 68 F i g . 23. R e s i d u a l s v s V S i n i 71 F i g . 24a. W(H7) vs S p e c t r a l Type by C l u s t e r and A s s o c i a t i o n . 7 4 F i g . 24b. W(H7) vs S p e c t r a l Type by L u m i n o s i t y C l a s s 74 v i F i g . 25a. D i s t a n c e M odulus v s Vo f o r P l e i a d e s Members 77 F i g . 25b. D i s t a n c e Modulus v s Vo f o r a P e r s e i Members 77 F i g . 26. R e s i d u a l s ( P e t r i e - P r e s e n t C a l i b r a t i o n ) 81 F i g . 27. R e s i d u a l s (BC - P r e s e n t C a l i b r a t i o n ) 82 F i g . 28. R e s i d u a l s ( C r a w f o r d - P r e s e n t C a l i b r a t i o n ) 83 F i g . 29. R e s i d u a l s ( L e s h - P r e s e n t C a l i b r a t i o n ) 84 F i g . 30. R e s i d u a l s (Blauuw - P r e s e n t C a l i b r a t i o n ) 85 F i g . 31. H/3 v s W(H7) 90 F i g . 32. V S i n i v s FWHM X4387 93 F i g . 33. V S i n i v s FWHM X4471 93 F i g . 34. V S i n i v s FWHM X4481 93 F i g . 35. V S i n i ( U e s u g i and Fukuda) v s V S i n i ( M i l l w a r d ) .94 F i g . 36. V S i n i ( B a l o n a ) v s V s i n i ( M i l l w a r d ) 94 F i g . 37. X4200/4471 v s S p e c t r a l Type 97 F i g . 38. X4471/4481 v s S p e c t r a l Type by L u m i n o s i t y C l a s s 98 F i g . 39. X4271/4481 v s S p e c t r a l Type by C l u s t e r ...99 F i g . A-1. Sample SB S p e c t r u m 107 F i g . A-2. Sample SB S p e c t r u m 108 F i g . A-3. Sample SB S p e c t r u m 109 F i g . A-4. Sample SB S p e c t r u m 110 F i g . A-5. Sample SB S p e c t r u m 111 F i g . A-6. Sample SB S p e c t r u m 112 Acknowledgements I would f i r s t l i k e t o t h a n k my s u p e r v i s o r , D r . Gordon W a l k e r , f o r h i s s u p p o r t and a d v i s e o v e r t h e p a s t two y e a r s . T h i s work would n o t have been c o m p l e t e d w i t h o u t h i s f r e q u e n t , p e r f e c t l y t i m e d , "Hang i n t h e r e " s t a t e m e n t s . My a p p r e c i a t i o n and h e a r t y t h a n k s go t o S t e p h e n s o n Yang f o r i n t r o d u c i n g me t c t h e R e t i c o n , RETICENT (n o t a n o t h e r b u g ! ) , and t h e l i f e o f t h e m e t r o p o l i t a n o b s e r v e r . A l s o , t h a n k s go t o t h e DAO f o r t h e g e n e r o u s a l l o t m e n t s o f o b s e r v i n g t i m e and t o J o hn N i c o l f o r p r o v i d i n g c l e a r w e ather on t h e September o b s e r v i n g r u n . F i n a l l y , t h a n k s t o C a t h y B e l l f o r h e r a s s i s t a n c e w i t h t h e f i n a l d r a f t . CB and HST 1 CHAPTER 1 : INTRODUCTION The d e t e r m i n a t i o n o f t h e l u m i n o s i t i e s , and hence d i s t a n c e s , o f e a r l y t y p e s t a r s i s o f paramount i m p o r t a n c e t o t h e s t u d y o f g a l a c t i c s t r u c t u r e and t h e i n t e r g a l a c t i c d i s t a n c e s c a l e . The f a c t t h a t t h e s e s t a r s c an be s e e n t o g r e a t d i s t a n c e s due t o t h e i r h i g h i n t r i n s i c l u m i n o s i t i e s and t e n d t o l i e i n t h e s p i r a l arms of g a l a x i e s , make them p r i m e c a n d i d a t e s t o s e r v e a s s p i r a l t r a c e r s . I t i s i m p o r t a n t , t h e n , t o a c c u r a t e l y c a l i b r a t e t h e a b s o l u t e m a g n i t u d e s o f t h e 0 and B - t y p e s t a r s b a s e d on some s t e l l a r o b s e r v a t i o n a l p a r a m e t e r , o r p a r a m e t e r s , t h a t c a n be u t i l i z e d f o r c l u s t e r and a s s o c i a t i o n s t a r s a s w e l l a s e a r l y t y p e f i e l d s t a r s . Many s u c h c a l i b r a t i o n s have been made o v e r t h e y e a r s u s i n g v a r i o u s methods ( J o h n s o n and I r i a r t e , 1 9 5 8 ; B l a a u w , l 9 6 3 ; Keenan, 1963; Weaver and E b e r t , l 9 6 4 ; Murphy,1969; F i t z G e r a l d , 1 9 6 9 ; C r a w f o r d , 1 9 7 8 ) . However, t h e agreement between c a l i b r a t i o n s i s i n some c a s e s as p o o r as ± 1 . 0 - 1 . 5 m a g n i t u d e s . The MK s p e c t r a l c l a s s i f i c a t i o n scheme d e v e l o p e d by Morgan and c o l l a b o r a t o r s i s p r o b a b l y t h e most w i d e l y u s e d c a l i b r a t i o n . I n t h i s two d i m e n s i o n a l s y s t e m , v a r i o u s l i n e r a t i o s , and i n t h e 2 c a s e o f e a r l y t y p e s t a r s , h y d r o g e n l i n e s t r e n g t h s , a r e e s t i m a t e d v i s u a l l y f r o m widened low d i s p e r s i o n s p e c t r a and compared t o a s e t o f e m p i r i c a l l y c h o s e n s p e c t r a w h i c h d e f i n e s p e c t r a l t y p e and l u m i n o s i t y c l a s s s e q u e n c e s . U s i n g t h i s s y s t e m , measurements w i t h a p r e c i s i o n o f a b o u t p l u s o r minus h a l f a s p e c t r a l t y p e a r e p o s s i b l e . T hen, u s i n g a s p e c t r a l t y p e - a b s o l u t e m a g n i t u d e c a l i b r a t i o n s u c h as t h a t d e v e l o p e d by Blaauw ( 1 9 6 3 ) , t h e i n t r i n s i c l u m i n o s i t i e s of t h e s t a r s may be f o u n d . The s t e l l a r d i s t a n c e modulus (V-Mv)o f o l l o w s d i r e c t l y f r o m a knowledge o f Vo, t h e a p p a r e n t m a g n i t u d e c o r r e c t e d f o r i n t e r s t e l l a r a b s o r p t i o n . The Blaauw c a l i b r a t i o n i s b a s e d on f i t t i n g t h e u n e v o l v e d main s e q u e n c e s o f v a r i o u s c l u s t e r s t o g e t h e r a l o n g a common l i n e i n a p l o t o f a p p a r e n t m a g n i t u d e (Vo) v s s p e c t r a l t y p e . The r e l a t i o n s ' z e r o p o i n t i s f i x e d by t h e Hyades c l u s t e r s e q u e n c e , t h e d i s t a n c e t o w h i c h i s f a i r l y w e l l known. The MK-l u m i n o s i t y c a l i b r a t i o n i s t h u s a q u i c k and r e l a t i v e l y e a s y method o f d e t e r m i n i n g t h e l u m i n o s i t i e s o f e a r l y t y p e s t a r s . However, t h e ra n g e o f a b s o l u t e m a g n i t u d e w i t h i n t h e l u m i n o s i t y c l a s s o f a g i v e n s p e c t r a l t y p e i s r a t h e r l a r g e ; due i n p a r t t o e v o l u t i o n a r y e f f e c t s . T h u s , w h i l e t h e MK s y s t e m may be a c c u r a t e f o r a s t a t i s t i c a l l y l a r g e sample of o b j e c t s t h e same c a n n o t be s a i d when i n d i v i d u a l s t a r s a r e c o n s i d e r e d . To compound t h i s p r o b l e m , t h e v i s u a l a p p e a r a n c e o f s p e c t r a l l i n e s o f a p a r t i c u l a r s t a r c an be e f f e c t e d by o t h e r f a c t o r s a s w e l l a s t h e i n t r i n s i c l i n e s t r e n g t h . F o r example t h e s p e c t r o g r a p h u s e d , t h e e x p o s u r e and d e v e l o p m e n t o f t h e p h o t o g r a p h i c p l a t e , and s t e l l a r p r o p e r t i e s s u c h a s r o t a t i o n . A l l t h i s c a n l e a d t o a m i s c l a s s i f i c a t i o n of i n d i v i d u a l s t a r s . 3 A n o t h e r drawback i s t h a t t h e n a t u r e o f t h e c l a s s i f i c a t i o n scheme t e n d s t o q u a n t i z e t h e r e s u l t s i n t o s p e c t r a l t y p e b i n s , e f f e c t i v e l y r e d u c i n g t h e s e n s i t i v i t y of a s p e c t r a l t y p e -i n t r i n s i c l u m i n o s i t y c a l i b r a t i o n . The MK c a l i b r a t i o n f o r e a r l y t y p e s t a r s i s u l t i m a t e l y d e p e n d e n t on t h e methods u s e d t o d e t e r m i n e t h e d i s t a n c e t o t h e Hyades c l u s t e r and on t h e d i s t a n c e i t s e l f , w h i c h has r e c e n t l y been r e v i s e d (Hanson 1979). T h i s d e p e n d e n c y i s due t o t h e f a c t t h a t t h e l o c a l s p a c e d e n s i t y o f 0 and B - t y p e s t a r s i s v e r y low. In f a c t , t h e r e a r e no OB s t a r s w i t h i n 20 pc o f t h e Sun and as s u c h r e l i a b l e d i s t a n c e s f r o m t r i g o n o m e t r i c p a r a l l a x e s c a n n o t be o b t a i n e d t o z e r o t h e e a r l y t y p e MK l u m i n o s i t y c a l i b r a t i o n s s u c h as B l a a u w ' s . In a d d i t i o n t o t h e above d r a w b a c k s , c l a s s i f i c a t i o n o f s t e l l a r s p e c t r a on t h e MK s y s t e m i s r a t h e r i n t e r p r e t i v e , d e p e n d i n g t o some e x t e n t on t h e o b s e r v e r and q u a l i t y o f s p e c t r a . I t would a p p e a r d e s i r a b l e t o use a more o b j e c t i v e and q u a n t i t a t i v e c r i t e r i a f o r d e t e r m i n i n g t h e i n t r i n s i c l u m i n o s i t i e s of e a r l y t y p e s t a r s . The v a r i a t i o n o f t h e s t r e n g t h of t h e h y d r o g e n Balmer l i n e s , e x p r e s s e d a s a f u l l w i d t h a t h a l f maximum, o r more p r e c i s e l y as an e q u i v a l e n t w i d t h , i s d e p e n d e n t on two f a c t o r s f o r e a r l y t y p e s t a r s : c o l l i s i o n a l b r o a d e n i n g and t e m p e r a t u r e . C o l l i s i o n a l b r o a d e n i n g a r i s e s due t o t h e d i r e c t c o l l i s i o n o f r a d i a t i n g atoms w i t h o t h e r p a r t i c l e s i n t h e s t e l l a r a t m o s p h e r e a n d / o r due t o t h e e f f e c t o f t h e e l e c t r o m a g n e t i c f i e l d o f s u r r o u n d i n g p a r t i c l e s on t h e e x c i t e d atoms ( S t a r k e f f e c t ) . C o l l i s i o n a l b r o a d e n i n g c a n be u n d e r s t o o d i n t e r m s o f t h e 4 H e i s e n b e r g u n c e r t a i n t y p r i n c i p l e . I f At i s t h e t i m e d u r i n g w h i c h an atom r a d i a t e s e n e r g y , t h e u n c e r t a i n t y i n t h i s e n e r g y , AE, i s A E A t ~ - f i o r 2nfiAv>At~' 1i t h u s AV— 1 2-nAt C o l l i s i o n s r e d u c e t h e l i f e t i m e o f a r a d i a t i n g s t a t e ; t h e r e f o r e , t h e more f r e q u e n t t h e c o l l i s i o n r a t e , t h e l a r g e r t h e u n c e r t a i n t y i n t h e r a d i a t i n g f r e q u e n c y and t h u s t h e b r o a d e r t h e s p e c t r a l l i n e . In S t a r k b r o a d e n i n g t h e e n e r g y l e v e l s of an e x c i t e d atom a r e a l t e r e d due t o an e l e c t r o s t a t i c f i e l d s e t up by s u r r o u n d i n g i o n s and e l e c t r o n s . T h i s s h i f t s t h e e m i t t i n g f r e q u e n c y of t h e l i n e . As t h e s e p e r t u r b a t i o n s a r e random t h e y r e s u l t i n a s y m m e t r i c b r o a d e n i n g o f t h e l i n e w i n g s . The c l o s e r t h e i n t e r a c t i n g p a r t i c l e s a r e t o t h e atom t h e l a r g e r t h e p e r t u r b a t i o n s and t h u s t h e c o l l i s i o n a l , o r p r e s s u r e , b r o a d e n i n g i s p r o p o r t i o n a l t o t h e d e n s i t y of t h e gas i n t h e s t e l l a r a t m o s p h e r e . T h e r e f o r e , t h e l i n e w i d t h i n c r e a s e s a s t h e s u r f a c e g r a v i t y i n c r e a s e s , w h i c h i n t u r n v a r i e s i n v e r s e l y as t h e l u m i n o s i t y . The S t a r k e f f e c t i s t h e d o m i n a n t b r o a d e n i n g mechanism f o r t h e h y d r o g e n Balmer l i n e s . 5 In a d d i t i o n , l i n e s t r e n g t h i s d e p e n d e n t on t e m p e r a t u r e . The l i n e i n t e n s i t y i s p r o p o r t i o n a l t o t h e number of atoms i n t h e f i r s t e x c i t e d s t a t e a s compared t o t h e number i n t h e g r o u n d and s i n g l y i o n i z e d s t a t e s . T h i s r a t i o r e a c h e s a maximum a t a p p r o x i m a t e l y 10,000 °K ( s p . t y . AO) and d e c r e a s e s a t h i g h e r t e m p e r a t u r e s (30,000°K a t s p . t y . B 0 ) . The r e a s o n f o r t h i s i s as f o l l o w s . From t h e B o i t z m a n e q u a t i o n t h e number d e n s i t y o f atoms i n t h e f i r s t e x c i t e d s t a t e o f h y d r o g e n (N2) i s r e l a t e d t o t h e number d e n s i t y i n t h e g r o u n d s t a t e (N1) by N2/N1 oc e x p ( - l / k T ) T h u s , N2 ( i e . t h e h y d r o g e n l i n e s t r e n g t h ) i n c r e a s e s w i t h i n c r e a s i n g t e m p e r a t u r e . However, f r o m t h e Saha e q u a t i o n , t h e r a t i o o f t h e number d e n s i t y i n any two n e i g h b o r i n g s t a g e s of i o n i z a t i o n N ( i + 1 ) and N ( i ) i s g i v e n by N( i + 1 ) ex. T""'"4- e x p ( - l / k T ) T h i s r a t i o w i l l i n c r e a s e a s t h e t e m p e r a t u r e i n c r e a s e s , b u t a t a f a s t e r r a t e t h a n N2/N1. T h e r e f o r e a t some p o i n t t h e h y d r o g e n l i n e s t r e n g t h s w i l l s t a r t t o d e c r e a s e as T i n c r e a s e s b e c a u s e most o f t h e h y d r o g e n w i l l be i o n i z e d and t h e number o f n e u t r a l 6 hydrogen atoms w i l l become n e g l i g i b l e . For hydrogen t h i s p o i n t i s a p p r o x i m a t e l y 10,000°K. Thus the l i n e s t r e n g t h w i l l d e c r e a s e f o r t y p e s e a r l i e r than AO as more and more of t h e hydrogen atoms are i o n i z e d . T h i s dependence on temperature i s of secondary importance as compared t o the S t a r k e f f e c t and t h e r e f o r e the s t r e n g t h of the hydrogen Balmer l i n e s i s m a i n l y a measure of s u r f a c e g r a v i t y and thus l u m i n o s i t y . As a r e s u l t , the hydrogen Balmer l i n e s , p a r t i c u l a r l y Hj3 and H 7 , a r e prime c a n d i d a t e s to s e r v e as l u m i n o s i t y i n d i c a t o r s . These two l i n e s a r e a t c o n v e n i e n t wavelengths t o o b s e r v e . They do not s u f f e r any major l i n e b l e n d s t h r o u g h o u t the s p e c t r a l range 0 t o e a r l y A, and the continuum i n the immediate v i c i n i t y of t h e l i n e s does not s u f f e r from l i n e c r o w d i n g t h a t t h e h i g h e r o r d e r hydrogen l i n e s encounter as they approach the Balmer d i s c o n t i n u i t y . T h i s c r o w d i n g makes the placement of the continuum l e v e l , n e c e s s a r y f o r the d e t e r m i n a t i o n of the l i n e s t r e n g t h s , v e r y d i f f i c u l t , i f -not i m p o s s i b l e . U s i n g narrow band uvby/3 photometry of e a r l y type c l u s t e r members C r a w f o r d (1978) has d e v e l o p e d an e m p i r i c a l B s t a r l u m i n o s i t y c a l i b r a t i o n based on the s t r e n g t h of the H/3 l i n e as d e r i v e d from the H/3 i n d e x . One major advantage of t h i s c a l i b r a t i o n i s t h a t i t s z e r o p o i n t i s not based on the d i s t a n c e t o the Hyades. I n s t e a d , the d i s t a n c e modulus of the P l e i a d e s , 5.54 magnitudes, has been used. T h i s v a l u e was found from a H/3 l u m i n o s i t y c a l i b r a t i o n f o r F s t a r s i n which P l e i a d e s member F s t a r s were used. The z e r o p o i n t of t h i s c a l i b r a t i o n i s based, i n t u r n , on r e l i a b l e t r i g o n o m e t r i c p a r a l l a x e s of F s t a r s . At V i c t o r i a , P e t r i e and h i s c o l l a b o r a t o r s 7 (1950,1953,1956,1965) d e v e l o p e d a c a l i b r a t i o n f o r 0, B and e a r l y A - t y p e s t a r s by e m p l o y i n g t h e s t r e n g t h of t h e H 7 l i n e r e d u c e d f r o m p h o t o g r a p h i c s p e c t r a o f i n d i v i d u a l s t a r s . W h i l e t h e H/3 i n d e x i s more a c c u r a t e t h a n p h o t o g r a p h i c e q u i v a l e n t w i d t h s o f H 7 , t h e l a t t e r h as t h e a d v a n t a g e o f b e i n g a b l e t o c o r r e c t f o r e m i s s i o n and l i n e b l e n d s . A l s o , a s p o i n t e d o u t by P e t r i e , s p e c t r a t a k e n f o r o t h e r p rograms c a n e a s i l y be u s e d f o r H 7 m e a s u r e s , making s e p a r a t e o b s e r v i n g p r o g r a m s u n n e c e s s a r y . In P e t r i e ' s r e v i s e d c a l i b r a t i o n ( 1 9 6 5 ) , 166 members i n 6 g a l a c t i c c l u s t e r s a nd a s s o c i a t i o n s ( t h e P l e i a d e s , a P e r s e i , NGC 2244, t h e U r s a M a j o r c l u s t e r , O r i o n OB1,and h & C h i P e r s e i ) were u s e d t o d e f i n e t h e H 7 - M V r e l a t i o n . The method u s e d i n c o n s t r u c t i n g t h e c a l i b r a t i o n i s a n a l o g o u s t o t h e c l u s t e r f i t t i n g p r o c e d u r e o f t h e p h o t o m e t r i c d i s t a n c e s c a l e , a l t h o u g h i n d e p e n d e n t from i t . S i n c e a l l t h e members i n e a c h c l u s t e r l i e a t a b o u t t h e same d i s t a n c e f r o m t h e Sun, t h e c l u s t e r s t a r s w i l l d e f i n e a common s e q u e n c e i n a W ( H 7)-Vo p l o t . A s i m i l a r s e q u e n c e i s p r o d u c e d f o r e a c h c l u s t e r u s e d ; d i s p l a c e d i n m a g n i t u d e due t o t h e f a c t t h a t t h e c l u s t e r s a r e a t v a r y i n g d i s t a n c e s f r o m t h e Sun and s h i f t e d i n W ( H 7 ) , d e p e n d i n g on t h e s p e c t r a l t y p e s i n t h e c l u s t e r . Two o v e r l a p p i n g c l u s t e r s e q u e n c e s c a n be b r o u g h t i n t o c o i n c i d e n c e by s l i d i n g , i n m a g n i t u d e , one c l u s t e r r e l a t i v e t o a n o t h e r . By u s i n g a number o f c l u s t e r s i n t h i s way, a s i n g l e s e q u e n c e c a n be c o n s t r u c t e d f o r t h e 0 t o e a r l y A - t y p e s t a r s . U t i l i z i n g t h e method j u s t d e s c r i b e d , t h e U r s a M a j o r c l u s t e r , a P e r s e i , O r i o n 0B1, NGC 2244, and h and C h i P e r s e i , i n t h a t o r d e r , were f i t t e d t o t h e P l e i a d e s c l u s t e r by P e t r i e t o d e f i n e t h e shape of t h e r e l a t i o n . 8 A t t h i s p o i n t , t h e p r o b l e m i s t o somehow z e r o t h e c a l i b r a t i o n so i t w i l l g i v e i n t r i n s i c l u m i n o s i t i e s , n o t j u s t l u m i n o s i t i e s r e l a t i v e t o t h e r e f e r e n c e , o r a n c h o r , c l u s t e r u s e d i n t h e f i t t i n g p r o c e d u r e . In o r d e r t o make t h e c a l i b r a t i o n i n d e p e n d e n t o f t h e Hyades c l u s t e r P e t r i e u s e d t h r e e d i f f e r e n t t y p e s of c a l i b r a t i n g s t a r s . T h e r e a r e a few e a r l y A - t y p e s t a r s w i t h r e l i a b l e t r i g o n o m e t r i c p a r a l l a x e s . T h e s e were u s e d and g i v e n h i g h w e i g h t i n g a s t h e y a r e t h e most f u n d a m e n t a l g r o u p . U n f o r t u n a t e l y , t h e r e a r e no B s t a r s i n t h i s g r o u p . S e c o n d l y , a g r o u p of v i s u a l b i n a r i e s composed o f an e a r l y - t y p e p r i m a r y and l a t e - t y p e s e c o n d a r y were u s e d ; t h e l a t t e r b e i n g f i t t e d t o t h e u n e v o l v e d c o l o r - m a g n i t u d e s e q u e n c e t o o b t a i n t h e a b s o l u t e m a g n i t u d e s o f t h e p r i m a r y components. And t h i r d l y , a g r o u p of e c l i p s i n g b i n a r i e s w i t h w e l l known a b s o l u t e d i m e n s i o n s were employed. W i t h t h e s e t h r e e g r o u p s he d e r i v e d a d i s t a n c e modulus f o r t h e P l e i a d e s , t h e a n c h o r c l u s t e r , o f 5.37 m a g n i t u d e s . P e t r i e i n c o r p o r a t e d t h e use o f " s p e c t r a l t y p e c o r r e c t i o n s " , w h i c h were t o be a p p l i e d t o t h e a b s o l u t e m a g n i t u d e s d e r i v e d f r o m h i s r e l a t i o n . T hese c o r r e c t i o n s were t o a c c o u n t f o r t h e weak dependence o f t h e W(H7) on t e m p e r a t u r e . They were f o u n d by d e t e r m i n i n g t h e a v e r a g e r e s i d u a l p e r s p e c t r a l t y p e f r o m t h e mean r e l a t i o n . T h e s e c o r r e c t i o n s were d i f f e r e n t f o r l u m i n o s i t y c l a s s e s I and I I - V . The c o r r e c t i o n s were s m a l l f o r t h e non-s u p e r g i a n t s , t y p i c a l l y ± 0 . 1 - 0 . 2 mag, b u t became a l a r m i n g l y l a r g e f o r t h e 0 s t a r s ; up t o +1.0 m a g n i t u d e s f o r s p e c t r a l t y p e 06. T h i s c o u p l e d w i t h t h e f a c t t h a t t h e d i s t a n c e modulus f o u n d from t h e f i t t i n g p r o c e d u r e f o r t h e e a r l i e s t t y p e c l u s t e r u s e d i n t h e r e l a t i o n , NGC 2244, was a n o m a l o u s l y low (9.7 ±0.1 mag), p u t t h e 9 q u e s t i o n o f t h e 0 s t a r c a l i b r a t i o n i n d o u b t . A c o m p a r i s o n w i t h Blaauw's (1963) c a l i b r a t i o n f o r main sequence o b j e c t s shows P e t r i e ' s c a l i b r a t i o n i s f a i n t e r by 1.3 m a g n i t u d e s f o r 06-08 s t a r s and 0.6 m a g n i t u d e s f a i n t e r f o r 09-B2 s t a r s . A l t h o u g h W a l b o r n (1972) c o n c l u d e s t h a t Blaauw's c a l i b r a t i o n i s t o o b r i g h t f o r t h e 09-B2 main s e q u e n c e s t a r s , W a l k e r and Hodge (1968) have a l s o s u g g e s t e d t h a t P e t r i e ' s 0 s t a r c a l i b r a t i o n i s i n f a c t up t o 1.5 m a g n i t u d e s t o o f a i n t . B a l o n a and Crampton (1974) ( h e r e a f t e r BC) r e i n v e s t i g a t e d t h e H 7 - M V r e l a t i o n u s i n g P e t r i e ' s H 7 e q u i v a l e n t w i d t h (EW) measures o f t h e P l e i a d e s , a P e r s e i , O r i o n 0B1, and P e r s e u s ' OBI members, s u p p l e m e n t e d w i t h t h e i r own p h o t o g r a p h i c m e asures o f S c o r p i u s - C e n t a u r u s , NGC 3293, NGC 4755, and IC 2944. Blaauw's (1963) d i s t a n c e modulus o f 5.55 m a g n i t u d e s f o r t h e P l e i a d e s was u s e d t o z e r o t h e r e l a t i o n . The agreement w i t h P e t r i e ' s r e l a t i o n i s f a i r l y good e x c e p t f o r t h e 0 s t a r s , where t h e r e s i d u a l s ( P e t r i e - B C ) a r e up t o +1.0 m a g n i t u d e s f o r t h e 06 s t a r s , t h u s c o n f i r m i n g t h e s u s p i c i o n s o f W a l k e r and Hodge. An i n t e r e s t i n g p o i n t i n t h i s r e g a r d , i s t h a t t h e r e s i d u a l s ( P e t r i e - B C ) a r e a l m o s t i d e n t i c a l t o P e t r i e ' s s p e c t r a l t y p e c o r r e c t i o n s , i m p l y i n g t h e r e would be e x c e l l e n t agreement f o r a l l s p e c t r a l t y p e s i f P e t r i e ' s (1965) c o r r e c t i o n s were i g n o r e d . BC a c t u a l l y p r o d u c e d two c a l i b r a t i o n s . One i s o f t h e form Mv = a + b ( l o g W ( H 7 ) ) , w i t h t h e (a) and (b) terms d e p e n d e n t on t h e s p e c t r a l t y p e o f t h e s t a r i n q u e s t i o n o v e r t h e r a n g e 06-A2. T h i s does away w i t h t h e 10 need f o r P e t r i e ' s form o f s p e c t r a l t y p e c o r r e c t i o n s . The o t h e r , i n v o l v i n g ( B - V ) o , w h i c h a l s o does n o t need s p e c t r a l t y p e c o r r e c t i o n s , was i n t r o d u c e d t o h e l p overcome t h e p r o b l e m o f a d i s c o n t i n u i t y i n t h e v a r i a t i o n of t h e (a) t e r m a t s p e c t r a l t y p e B4 i n t h e l o g r e l a t i o n . The mean d i f f e r e n c e between t h e two c a l i b r a t i o n s i s + 0 . 0 4 ± 0 . 2 m a g n i t u d e s f o r t h e 270 s t a r s u s e d . The BC c a l i b r a t i o n i s 0.4 mag. f a i n t e r t h a n Blaauw's f o r l u m i n o s i t y c l a s s e s I I I - V e a r l i e r t h a n B2 and 0.3 mag. b r i g h t e r f o r t h e B3-B6 V s t a r s . The 09-B2 main s e q u e n c e c a l i b r a t i o n i s f a i n t e r t h a n Blaauw's, w h i c h i s i n t h e r i g h t s e n s e i f i n f a c t t h e Blaauw c a l i b r a t i o n i s t o o b r i g h t o v e r t h i s s p e c t r a l r a n g e , as W a l b o r n has s u g g e s t e d . As m e n t i o n e d above, BC r e l i e d on Blaauw's d i s t a n c e modulus f o r t h e P l e i a d e s t o e s t a b l i s h t h e z e r o p o i n t o f t h e c a l i b r a t i o n . T h i s r e n d e r s t h e c a l i b r a t i o n d e p e n d e n t on t h e d i s t a n c e t o t h e Hya d e s . As t h e d i s t a n c e modulus o f t h i s c l u s t e r has been r e c e n t l y r e v i s e d f r o m 3.1 t o 3.3 m a g n i t u d e s , one wo u l d e x p e c t a c o r r e s p o n d i n g change i n t h e z e r o p o i n t of t h e BC c a l i b r a t i o n . I t s h o u l d a l s o be n o t e d t h a t a l t h o u g h e s s e n t i a l l y i n d e p e n d e n t o f t h e H yades, P e t r i e ' s z e r o p o i n t method g i v e s a d i s t a n c e modulus of 5.37 m a g n i t u d e s f o r t h e P l e i a d e s . T h i s v a l u e i s some 0.2 m a g n i t u d e s s m a l l e r t h a n t h a t o f C r a w f o r d (1976) w h i c h i s b a s e d on t h e t r i g o n o m e t r i c p a r a l l a x e s of F s t a r s , and t h a t o f Blaauw (1963) w h i c h i s b a s e d on a Hyades d i s t a n c e modulus o f 3.1. W i t h t h e s u b s e q u e n t i n c r e a s e i n t h i s d i s t a n c e t h e d i s c r e p a n c y between t h e P e t r i e a n d Blaauw v a l u e s becomes e v e n l a r g e r . An i n t e r e s t i n g a s p e c t o f t h e BC c a l i b r a t i o n i s t h e d i s c o n t i n u i t y i n t h e v a r i a t i o n o f t h e (a) c o e f f i c i e n t , w h i c h 11 i m p l i e s some form of d i s c o n t i n u i t y i n the W(H7>-Mv r e l a t i o n . An i n s p e c t i o n of P e t r i e ' s c a l i b r a t i o n shows no such f e a t u r e . I t would appear u s e f u l t o p e r f o r m a r e c a l i b r a t i o n of the H7-MV r e l a t i o n , based on P e t r i e ' s (1965) method, because of the r e s i d u a l s noted above between the v a r i o u s c a l i b r a t i o n s , the anomalously low v a l u e of the P e t r i e NGC 2244 d i s t a n c e modulus, and the u n c e r t a i n t y of a d i s c o n t i n u i t y i n the r e l a t i o n . T h i s i s even more apparent when one c o n s i d e r s t h a t t h e s e c a l i b r a t i o n s have been c o n s t r u c t e d u t i l i z i n g p h o t o g r a p h i c s p e c t r a . The i n t r o d u c t i o n of s o l i d s t a t e d e t e c t o r s i n subsequent y e a r s now a l l o w s f o r h i g h e r q u a l i t y s p e c t r a t o be o b t a i n e d , and thus h o p e f u l l y , more p r e c i s e e q u i v a l e n t w i d t h s . W i t h h i g h s i g n a l t o n o i s e d a t a ( i e . >100:1), l i n e b l e n d s become more ap p a r e n t and can be c o r r e c t e d , continuum l e v e l s a c c u r a t e l y l o c a t e d , and s p e c t r o s c o p i c b i n a r i e s , u n doubtedly one of the l a r g e r p o s s i b l e s o u r c e s of e r r o r i n the c a l i b r a t i o n , i d e n t i f i e d and p a r t i a l l y c o r r e c t e d . A l l the above w i l l h o p e f u l l y l e a d t o a more a c c u r a t e H7-MV c a l i b r a t i o n w i t h l e s s s c a t t e r about the mean r e l a t i o n (BC mean d i s p e r s i o n = ±0.5 mag.). Hence, a program was i n i t i a t e d t o o b t a i n R e t i c o n s p e c t r a of a number of P e t r i e ' s c a l i b r a t i o n s t a r s a l o n g w i t h new o b j e c t s . H i s method of z e r o i n g the r e l a t i o n i s c l o s e l y f o l l o w e d as i t r e s u l t s i n an e s s e n t i a l l y independent c a l i b r a t i o n . The new e m p i r i c a l c a l i b r a t i o n i s p r e s e n t e d h e r e . E v o l u t i o n a r y and s t e l l a r r o t a t i o n e f f e c t s a r e examined. In a d d i t i o n , p r o j e c t e d a x i a l r o t a t i o n v e l o c i t i e s , V s i n i , a r e p r e s e n t e d f o r most program s t a r s as w e l l as a s p e c t r a l c l a s s i f i c a t i o n scheme. 12 CHAPTER 2 : THE OBSERVATIONS R e t i c o n s p e c t r a o f 83 o f t h e b r i g h t e s t e a r l y t y p e s t a r s i n 8 g a l a c t i c c l u s t e r s and a s s o c i a t i o n s a s w e l l a s 36 e a r l y t y p e z e r o p o i n t s t a r s ( e c l i p s i n g b i n a r i e s , v i s u a l b i n a r i e s , and s t a r s w i t h a c c u r a t e t r i g o n o m e t r i c p a r a l l a x e s ) were o b s e r v e d d u r i n g 18 n i g h t s a t t h e D o m i n i o n A s t r o p h y s i c a l O b s e r v a t o r y . The d a t e s a r e l i s t e d i n t a b l e I . A l l o b s e r v a t i o n s were c a r r i e d o ut w i t h t h e 1.22 meter t e l e s c o p e and a l i q u i d n i t r o g e n c o o l e d RL1872 F/30 R e t i c o n d i o d e a r r a y d e c t e c t o r w h i c h was b u i l t a t UBC (Walke r 1977). A 300 line/mm g r a t i n g b l a z e d a t X5000 gave a r e c i p r o c a l o o d i s p e r s i o n o f 40 A/mm (0.6 A / d i o d e ) a t H 7 a l l o w i n g t h e s p e c t r a l r e g i o n f r o m a p p r o x i m a t e l y XX4000-5000 t o be c o v e r e d . An e f f o r t was made t o o b t a i n s p e c t r a w i t h a s i g n a l - t o - n o i s e r a t i o >150:1, a l t h o u g h f o r some f a i n t e r s t a r s t h i s s i g n a l l e v e l was not r e a c h e d . The c l u s t e r and a s s o c i a t i o n members o b s e r v e d a r e l i s t e d i n t a b l e I I I ; t h e z e r o p o i n t c o r r e c t i o n s t a r s i n t a b l e IV. In t a b l e I I I , column (1) g i v e s t h e s t a r ' s HD number, (2) o t h e r d e s i g n a t i o n s i f a v a i l a b l e , (3) t h e s p e c t r a l t y p e from t h e Table I Dates of O b s e r v a t i o n s Dates (UT) Number of N i g h t s September 7-13,1981 7 October 22,1981 1 December 6,1981 1 F e b u r a r y 3-8,1982 6 March 4-6,1982 3 14 l i t e r a t u r e , (4) t h e a p p a r e n t v i s u a l m a g n i t u d e , Vo, c o r r e c t e d f o r i n t e r s t e l l a r r e d d e n i n g , t a k e n f r o m t h e l i t e r a t u r e , (5) t h e measured H 7 e q u i v a l e n t w i d t h i n a n g s t r o m s , (6) t h e m e a s u r e d r o t a t i o n a l v e l o c i t y , V s i n i , i n km/sec, (7-10) c e n t r a l l i n e d e p t h s as a f r a c t i o n o f t h e c o n t i n u u m l e v e l , (11) t h e a b s o l u t e m a g n i t u d e , Msp, d e t e r m i n e d f r o m t h e H 7 - M V c a l i b r a t i o n , (12) t h e number o f s p e c t r a u s e d i n d e t e r m i n i n g t h e W ( H 7 ) , (13) t h e s i g n a l - t o - n o i s e l e v e l of t h e s p e c t r a , and (14) t h e comments on t h e i n d i v i d u a l s t a r s . The u n r e f e r e n c e d s p e c t r o s c o p i c b i n a r y (SB) comments o r i g i n a t e from v i s u a l i n s p e c t i o n of t h e R e t i c o n s p e c t r a . T a b l e IV i s s i m i l a r e x c e p t f o r column (I1),m-M, w h i c h g i v e s t h e z e r o p o i n t c o r r e c t i o n s . B r a c k e t e d v a l u e s were n o t i n c l u d e d i n t h e d e t e r m i n a t i o n o f t h e f i n a l c o r r e c t i o n v a l u e . C l u s t e r s o b s e r v e d i n c l u d e t h e P l e i a d e s (M45), NGC 2244, NGC 2264, U r s a M a j o r (Cr 2 8 5 ) , and a P e r s e i (Mel 2 0 ) , a l o n g w i t h t h e O r i o n OB1, Cygnus OB7, and Cepheus 0B3 a s s o c i a t i o n s . Of t h e s e g r o u p s NGC 2264, Cyg OB7, and Cep OB3 were n o t u s e d i n P e t r i e ' s (1965) r e v i s e d c a l i b r a t i o n . They have been added h e r e t o h e l p s t r e n g t h e n t h e h i g h l u m i n o s i t y end o f t h e r e l a t i o n . However, a s c a n be s e e n from t a b l e I I I , o n l y one member of NGC 2264 (HD 47887) was o b s e r v e d , and t h e r e f o r e t h i s c l u s t e r i s of l i m i t e d v a l u e . The s t e l l a r g r o u p s p r o v i d e good o v e r l a p p i n g c o v e r a g e o a l o n g t h e e n t i r e H 7 - M V r e l a t i o n e x c e p t f o r t h e 10-14 A EW r e g i o n where P l e i a d e s members a r e t h e o n l y s t a r s . T h i s u n f o r t u n a t e s i t u a t i o n o c c u r s due t o t h e l a c k o f a P e r s e i members o b s e r v e d . The uvby/UBV p h o t o m e t r y and i n t e r s t e l l a r r e d d e n i n g c o r r e c t i o n s were t a k e n f r o m t h e l i t e r a t u r e ; t h e s o u r c e s a r e l i s t e d i n t a b l e I I . In t h e c a s e o f NGC 2244, H e i s e r ' s T a b l e I I C l u s t e r and A s s o c i a t i o n Photometry S t e l l a r Group P l e i a d e s NGC 2244 NGC 2264 a P e r s e i O r i o n OB 1 Source C r a w f o r d and P e r r y (1976) P e t r i e (1965) H e i s e r (1977) Johnson (1962) Mendoza and Gomez (1980) C r a w f o r d and Barnes (1974) P e t r i e and Heard (1970) Warren and Hesser (1978) Cepheus 0B3 Cygnus 0B7 UMa C l u s t e r G a r r i s o n (1970) Humphreys (1978) Eggen (1965) C r a w f o r d and Barnes (1969) 16 c o r r e c t i o n s were a p p l i e d t o J o h n s o n ' s (1962) o r i g i n a l UBV d a t a f o r HD 46150, as H e i s e r d o e s n o t l i s t i t and Vo f o r HD 47382 (a s u s p e c t e d non-member) was t a k e n from Humphreys ( 1 9 7 8 ) . O n l y " i n n e r " members of t h e c l u s t e r were u s e d i n t h e c a l i b r a t i o n t o i n s u r e t h a t a l l s t a r s were i n f a c t t r u e members l y i n g a t t h e same d i s t a n c e . The v i s u a l e x t i n c t i o n c o r r e c t i o n , Av, n o t g i v e n by Humphreys f o r t h e Cyg OB7 member, HD 199579, was o b t a i n e d by t h e a u t h o r f r o m a p l o t o f Av v e r s u s t h e c e n t r a l d e p t h o f t h e X4430 i n t e r s t e l l a r l i n e f o r t h e o t h e r member s t a r s g i v e n by Humphreys f o r w h i c h R e t i c o n s p e c t r a were a v a i l a b l e . The p l o t i s shown i n f i g u r e 1. The c o r r e l a t i o n i s q u i t e good ( l i n e a r r e g r e s s i o n c o e f f i c i e n t = 0.82) and t h e d e r i v e d v a l u e o f Av=+0.75 mag. was a p p l i e d t o V, t h e u n c o r r e c t e d v i s u a l m a g n i t u d e . In a l l c a s e s t h e r a t i o o f t o t a l - t o - s e l e c t i v e a b s o r p t i o n R(B-V)=3 was u s e d t o o b t a i n t h e c o r r e c t e d a p p a r e n t m a g n i t u d e Vo. T h r e e c l u s t e r s d e s e r v e s p e c i a l m e n t i o n i n t h i s r e g a r d . J o h n s o n (1965) s u g g e s t s a R(B-V) v a l u e o f 5.4 f o r Cep OB3. However, B e c k e r ( 1 9 6 6 ) , G a r r i s o n ( 1 9 7 0 ) , and C r a w f o r d & B a r n e s (1970) a l l c o n c l u d e t h a t a v a l u e o f R=3 i s more a p p r o p r i a t e and t h a t v a l u e has been u s e d h e r e . Warren and H e s s e r (1978) f i n d an R(B-V) o f 3 f o r t h e O r i o n OB1 b s u b g r o u p and t h a t v a l u e has been u s e d t h r o u g h o u t t h e i r work. But, t h e y do n o t e t h a t t h i s v a l u e may n o t be a p p r o p r i a t e f o r a l l t h e s u b g r o u p s . F i n a l l y , many a u t h o r s have e x p r e s s e d c o n c e r n o v e r a p o s s i b l e r e d d e n i n g g r a d i e n t a c r o s s NGC 2244. H e i s e r ( 1 9 7 7 ) , however, f i n d s no s y s t e m a t i c e f f e c t s a c r o s s t h e c l u s t e r and a v a l u e o f R(B-V)=3 has been u s e d f o r a l l o b s e r v e d members. U n d o u b t e d l y one of t h e l a r g e r , i f n o t t h e l a r g e s t , p o s s i b l e 17 2 . 5 a > cr H D 199579 A v = 0-75 m a g 8.0 Central Depth of A 4430 (% of Qmtinwm) FIG. l o The v i s u a l e x t i n c t i o n c o r r e c t i o n Av, i n magnitudes, (from Humphreys 1978) vs the measured c e n t r a l depth o f \4430 f o r members of the Cyg 0B7 a s s o c i a t i o n . The l i n e a r l e a s t squares f i t has been made to the c i r c l e d p o i n t s . HD 199579 has been f i t t e d to t h i s l i n e to determine i t s Av. 18 sources of e r r o r in c o n s t r u c t i n g and a p p l y i n g a W(H7 ) - M v c a l i b r a t i o n i s tha t of d u p l i c i t y . Unknown secondary components w i l l cause the a p p a r e n t , and hence a b s o l u t e magni tudes , of o b j e c t s to be anomalous ly b r i g h t , a n d , depending on the s p e c t r a l type of the secondary , may contaminate the W ( H 7 ) . P e t r i e made no attempt to c o r r e c t the apparent magnitudes of c l u s t e r members f o r d u p l i c i t y i n h i s c a l i b r a t i o n s , except i n cases where the UBV photometry he employed had done so and f o r s p e c t r o s c o p i c b i n a r i e s where Am was known. An attempt to c o r r e c t f or d u p l i c i t y in cases where Am was unknown was made i n the BC c a l i b r a t i o n (AV = +0.1 mag. f or a s i n g l e - l i n e d s p e c t r o s c o p i c b i n a r y ( v a r i a b l e v e l o c i t y ) and AV = +0.2 mag. i n cases where a secondary component was s u s p e c t e d ) . The h i g h S/N R e t i c o n s p e c t r a o b t a i n e d f o r the present s tudy are p a r t i c u l a r l y u s e f u l i n d e t e c t i n g secondary component l i n e b l ends and thus a t tempts at c o r r e c t i n g for d u p l i c i t y have been made as f o l l o w s . (1) Secondary component suspec ted from l i t e r a t u r e , no secondary suspec ted from present d a t a AV = 0.0 mag (2) V a r i a b l e v e l o c i t y from l i t e r a t u r e AV = +0.1 mag ( 3 ) V a r i a b l e v e l o c i t y and suspec ted secondary component from l i t e r a t u r e a n d / o r p r e s e n t data AV = +0.1 mag 19 (4) S e c o n d a r y component f o u n d f r om t h e p r e s e n t d a t a AV = +0.2 mag (5) D o u b l e l i n e s p e c r o s c o p i c b i n a r y ( S B ) , c o r r e c t i o n s made a c c o r d i n g t o t h e Am between t h e two components T h e s e c o r r e c t i o n s may i n f a c t be t o o c o n s e r v a t i v e , b u t were c h o s e n t o r e f l e c t t h o s e made by BC i n t h e i r c a l i b r a t i o n . T h i s was done so t h a t i n c o m p a r i n g t h e p r e s e n t c a l i b r a t i o n t o t h a t o f BC, t h e most w i d e l y u s e d W(H7)-Mv r e l a t i o n , any s y s t e m a t i c d i f f e r e n c e s o b s e r v e d would not be due t o d u p l i c i t y c o r r e c t i o n s but some o t h e r f a c t o r t h a t m i g h t be i d e n t i f i e d . A l s o , w h i l e i t i s o b v i o u s l y n e c e s s a r y t o c o r r e c t f o r d o u b l e s , i t a p p e a r s u s e f u l t o u n d e r c o r r e c t a s d i s t a n t f a i n t s t a r s t h a t m i g h t be a p p l i e d t o th e c a l i b r a t i o n , i n f o r example g a l a c t i c s t r u c t u r e - S t u d i e s , would p r o b a b l y be u n c o r r e c t e d i f t h e y were i n f a c t c l o s e d o u b l e s . In s i t u a t i o n s s u c h as ( 5 ) , where Am was known, c o r r e c t i o n s were made t o t h e W(H7) f o l l o w i n g P e t r i e ( 1 9 5 3 ) , and a r e d e s c r i b e d below, w i t h t h e m o d i f i c a t i o n t h a t t h e l i g h t r a t i o o f th e s e c o n d a r y - t o - p r i m a r y , ( 1 ) , was n o t r e s t r i c t e d t o =^0.5. T h i s was not a s e r i o u s d e p a r t u r e f r o m t h e method a s Am was known f o r o n l y 6 c l u s t e r s t a r s u s e d i n t h e c a l i b r a t i o n ( a l l i n O r i o n OB1). Of t h e s e , 4 s e c o n d a r i e s were u s e d , t h e l i g h t r a t i o s a r e 0.36, 0.40, 0.40, and 0.44. The o t h e r two a t 0.16 were d i s c a r d e d . A number o f new SB c a n d i d a t e s were f o u n d from v i s u a l i n s p e c t i o n o f th e s p e c t r a ( s e e A p p e n d i x A ) . I f an o b j e c t was p r e v i o u s l y an 20 unknown SB, c o r r e c t i o n (4) was a p p l i e d o n l y i f t h e p r e s e n c e of a s e c o n d a r y component was f a i r l y c e r t a i n . The a b s o l u t e m a g n i t u d e s o f t h e e c l i p s i n g b i n a r i e s o A q u i l a e and AH C e p h e i were o b t a i n e d from L a c y ( 1 9 7 9 ) ; t h e r e s t a r e from Popper ( 1 9 8 0 ) . Of t h e s e , P o p p e r s t a t e s t h e masses and r a d i i o f RX Her, AR Aur, and /UAur a r e known t o an a c c u r a c y o f 15% o r b e t t e r w h i l e Y Cyg, U Oph, and AG Per a r e known t o b e t t e r t h a n 20%. I t w i l l be n o t e d i n t a b l e IV t h a t most o f t h e e c l i p s i n g b i n a r i e s s u p p l y 2 H 7 EW v a l u e s w h i l e o n l y one was m e a s u r e d . T h i s has been done f o l l o w i n g t h e p r o c e d u r e o u t l i n e d by P e t r i e ( 1 9 5 3 ) . I n an e a r l y t y p e s p e c t r o s c o p i c b i n a r y s y s t e m , t h e o b s e r v e d W (H7) i s t h e mean o f two components. Thus Wp = W - 1 AW 1+1 Ws = W + 1 AW 1+1 where Wp and Ws a r e t h e H 7 EWs o f t h e p r i m a r y and s e c o n d a r y r e s p e c t i v e l y , W i s t h e o b s e r v e d W ( H 7 ) , (1) t h e l i g h t r a t i o o f t h e s e c o n d a r y - t o - p r i m a r y , and AW t h e e x p e c t e d change i n t h e W (H7) f r o m t h e m a g n i t u d e d i f f e r e n c e o f t h e two components. AW c a n be o b t a i n e d from a p r e l i m i n a r y c a l i b r a t i o n o f t h e W ( H 7)-Vo (Mv) r e l a t i o n , and i f (1) i s known t h e W (H7) may be f o u n d f o r e a c h o f t h e s y s t e m s ' components. T h e r e a r e two l i m i t i n g c a s e s , (1) where 1 = 1 and 21 (2) where 1—>0. In case (1) AW •= 0 and thus the above r e l a t i o n s f o r Wp and Ws become t r i v i a l . In case (2) the observed spectrum i s e s s e n t i a l l y that of the b r i g h t e r component and the d e t e r m i n a t i o n of AW i s l i k e l y to be in e r r o r as the s p e c t r a l types of the two components may d i f f e r s u b s t a n t i a l l y . As a r e s u l t , the e c l i p s i n g b i n a r y s e c o n d a r i e s were on ly used i f (1) was l e s s than 1.0 and g r e a t e r than or equa l to 0 . 5 . M o d i f i c a t i o n of t h i s lower l i m i t of (1) f o r O r i o n OB1 members has been d e s c r i b e d above . The v i s u a l b i n a r y data i s from Eggen (1963) . H i s l u m i n o s i t i e s were d e r i v e d by f i t t i n g the secondary components of the systems to the Hyades main sequence a f t e r c o r r e c t i n g the observed (B-V) for l i n e b l a n k e t i n g and redden ing e f f e c t s . Table I I I C l u s t e r and A s s o c i a t i o n Data : HD : Number : Other Des i g. Sp. Type • Vo : Hr Vs i n i C e n t r a l Depth Msp • 4200 : Hel I 4387 Hel 4471 Hel 4481 Mg l l PLEIADES • 22578 -- AO 6 . 70 15.4 2 12* - - 0.039 0.090 1 . 1 : 23288 16 Tau B7IV 5.07 8.8 256 - 0.061 0.097 0.076 -0.4 : 23302 17 Tau B6111 3.81 6.8 222 - 0.077 0.117 0.077 -1.4 : 23324 18 Tau B8V 5.76 9 . 5 294 - 0.052 0.075 0.063 -0.2 23338 19 Tau B6V 4 . 34 7 . 3 160 - 0.089 0. 136 0. 108 -1.2 23408 20 Tau B7111 3.92 6.3 46 - 0.076 0.116 0. 120 -1.7 : 23432 21 Tau B8V 5.60 10. 5 2G0 - 0.058 0.064 0. 102 0. 1 : 23441 22 Tau B9V 6.28 12.7 131 - 0.058 0.046 0.085 0.7 : 23480 23 Tau B6IV 4.17 6.2 255 - 0.070 0.093 0.055 -1.8 23568 -- B9.5V 6 .55 13.8 257* - 0.030 0.018 0.075 0.9 : 23630 n Tau B7111 3.01 5.9 202 - 0.077 0.112 0.099 -2.0 23631 -- A2m 6.93 16.8 146* - - 0.062 0.317 1 . 3 23642 -- AOV 6.71 15.2 58* - - 0.045 0. 246 1 . 1 S/N Comments 100 250 800 250 550 650 180 150 430 180 1300 1 10 200 SB?; NM(P,=arce et a l 1975) OFC SB; OB(Craw,-ord et a l 1976); Vo c o r r e c t e d by 0.2 SB?; RV V a r ( P e a r c e et a l 1975); Vo c o r r e c t e d by 0.1 SB; RV V a r ( P e a r c e e t a l 1975); Vo c o r r e c t e d by 0.2 SB1?(Crawford et a l 1976); RV V a r ( P e a r c e et a l 1975); Vo c o r r e c t e d by 0.1 SB; Vo c o r r e c t e d by 0.2 SB from spectrum?, SB from p o s i t i o n i n H-y-Vo diagram? SB; Vo c o r r e c t e d by 0.2 SB; Vo c o r r e c t e d by 0.2 SB?(Crawford et a l 1976) SB2(Crawford et a l 1976); RV V a r ( P e a r c e et a l 1975); Vo c o r r e c t e d by 0.2 : : : C e n t r a l Depth : : : : HD : Other : Sp. Vo : Hy : V s i n i : : Msp : n : S/N : Comments Number : D e s i g . : Type : 4200 : 4387 : 4471 : 4481 : : : : : : : : : : H e l l Hel : Hel : Mg l l : : : : 23753 B8V 5 46 : 8 4 330 0 048 0 052 0 048 -0 6 1 300 RV V a r ( P e a r ~ e et a l 1975); Vo c o r r e c t e d by 0.1 23763 -- A 1V 7 10 18 4 135* - - 0 023 0 168 1 5 ! 200 RV V a r ( P e a r c e et a l 1975); Vo c o r r e c t e d by 0.1 23850 27 Tau B8III 3 75 6 9 236 - 0 044 0 060 0 070 -1 4 1 700 SB; Vo c o r r e c t e d by 0.2 23862 28 Tau B8pV 4 97 3 2 190* _ _ 0 162 -4 1 1 300 Hp em., OFC from p o s i t i o n in Hy-Vo diagram : 23873 -- B9.5V 6 52 14 0 107 - 0 038 0 040 0 162 0 9 1 240 23913 . _ B9 6 93 16 6 146* _ _ 0 048 0 107 1 3 1 150 SB; p r o b a b l e NM(Pearce e t al 1975), OFC 23923 •- B9V 6 07 1 1 1 311 - 0 040 0 038 0 051 0 3 1 200 : 23950 _ B8III 5 92 8 6 74 _ 0 062 0 062 0 120 -0 5 1 150 SB?; p o s s i b l e NM(Pearce et a l 1975), NM from p o s i t i o n i n Hy-Vo di a . , 0 F C • 23964 - AOV 6 57 14 1 - 10 - 0 040 . 0 042 0 162 0 9 1 170 SB1(Crawford et a l 1976); RV V a r ( P e a r c e et a l 1976); Vo c o r r e c t e d by 0.2 24076 - A2V 6 53 16 2 182* - - 0 015 0 131 1 3 1 160 SB from spectrum?, SB from p o s i t i o n i n Hy-Vo diagram? : : : : : C e n t r a l Depth : : : HD : Other : Sp. : Vo : Hy : V s i n i : : Msp : n : S/N : Comments Number : D e s i g . : Type : : 4200 : 4387 : 4471 : 4481 : : : : : : : : : : H e l l Hel : Hel : Mgl l : : : : ORION 0B1 35039 22 O r i B2Vs 4 .78 4 5 19 - 0 317 0 388 0 152 -3 1 1 300 SB; Vo c o r r e c t e d by 0.2 35149 23 O r i B2 . 5V 4 90 4 9 236 0 113 0 165 0 044 -2 7 1 240 SB; Vo c o r r e c t e d by 0.2 - 0 081 - 0 032 3541 1A n O r i B1IV 3 9 4 0 138 - 0 185 0 266 0 074 -3 4 1 320 SB; Am=0.9 mag, Vo f o r A B d 8 4 6 253** - 0 083 0 114 0 029 -3 0 component c o r r e c t e d by 0.8(Warren et a l 1978) 35715A <)< O r i BO. 5V 4 8 4 8 167 - 0 173 0 209 0 051 -2 8 1 150 SB; Am=1.0 mag, Vo f o r A B 5 8 5 3 150** - 0 067 0 101 0 053 -2 4 component c o r r e c t e d by 0.4(Warren et a l 1978) 35899 B3V 7 4 7 5 244 — 0 157 0 190 0 074 -1 1 2 130 SB? 36486 6 O r i A 0911 2 2 1 9 191 0 056 0 083 0 195 0 034. -5 6 1 1 100 i SB; Vo c o r r e c t e d by 0.2 - (Warren e t a l 1978) 36512 v O r i BOVs 4 76 3 5 28 0 063 0 226 0 326 0 071 -3 9 1 260 SB; Vo c o r r e c t e d by 0.2 36822 o> o n BOIII 4 15 3 3 36 0 078 0 235 0 315 0 085 -4 0 1 170 NM 36960 B0.5V 4 71 3 6 40 0 022 0 244 0 319 0 076 -3 8 1 260 No Hp em. (Warren e t a l 1978 r e p o r t p o s s i b l e Hp em. ) 37016 - - B2V 6 6 7 3 143 0 017 0 204 0 246 0 089 -1 2 2 350 SB; Vo c o r r e c t e d by 0.5 (Warren e t a l 1978) 37018 42 O r i B 1V 4 5 4 0 132 o 022 0 205 0. 269 0 070 -3 4 1 140 Vo c o r r e c t e d by 0.1 f o r d u p l l e i t y ( W a r r e n e t a l 1978) 37022 6 O r i C 06p 4 28 2 3 1 13 0 097 0 072 0. 182 0 043 -5 1 1 250 Hy and Hp em.; OFC from p o s i t i o n i n Hr _ V o p l o t 37023 9 O r i D BO.5Vp 5 61 - - - - - - 1 50 Hr and Hp em., OFC 37041 6 O r i A 09 . 5V 4 7 _ _ _ _ 1 _ Hr and Hp em., OFC; Vo c o r r e c t e d by 0.24 (Warren et a l 1978) HD Number Other D e s i g . Sp. Type Vo HT Vs i n i C e n t r a l Depth 4200 H e l l 4387 Hel 4471 Hel 4481 Mgll Msp S/N Comments 37043A L Or i : 0 9 I II : 2 .8 : 2 . 3 : 60 : 0 106 • 0 072 0 182 0 033 : -5 1 : 1 150 SB; Am=1.99(Batten 1967) Vo c o r r e c t e d by 0.2; Sec. comp. not used as 1=0.16 37055 : B4V : S 45 8 .2 : 179 0 186 0 233 0 094 -0 7 • 2 210 SB; Vo c o r r e c t e d by 0.2 37128 6 Or i : BOIa 1 28 : 1 6 109 : 0 052 0 139 0 302 0 046 -6 1 • 1 800 No Hp em. (Warren e t a l 1978 r e p o r t p o s s i b l e Hp em. ) 37397 B4V 6 73 6 3 274 0 029 0 146 0 179 0 066 -1 7 1 100 SB? 37468A Or i 09 ,5V 3 99 3 4 172 0 059 0 153 0 213 0 041 -3 9 1 120 Vo c o r r e c t e d by 0.36 f o r B B 4 99 4 1 - - - - - -3 4 comp.(Am=1.0) and 0.1 f o r C and D(Warren et a l 1978) 37742 £ Or i 09.5Iab 1 8 1 7 138 0 063 0 095 0 200 0 029 -5 9 1 600 Vo c o r r e c t e d by 0.1 f o r SB(Warren e t a l 1978), Sec comp not used as 1=0.16 37756A -- B2V+B 5 1 4 9 106 - 0 217 0 294 0 080 -2 7 2 380 Vo c o r r e c t e d by 0.3 f o r B 6 2 5 9 148* - 0 081 - 0 043 -2 0 SB(Am=1.1) (Warren et a l 1978) 38771 K Or i BO.51 a 1 68 1 8 1 10 O 042 0 177 0 270 0 055 -5 8 1 330 No Hp em. (Warren et a l 1978 r e p o r t p o s s i b l e Hp em. ) PERSEI 20418 31 Per B5Vn 4 9 6 7 298 - 0 095 0 128 0 050 -1 5 400 SB; Vo c o r r e c t e d by 0.2 20809 •- B5V 5 5 7 4 250 - 0. 124 0 169 0 068 -1 1 380 SB; Vo c o r r e c t e d by 0.2 21071 - B7Vsn 5 9 8 8 83 - 0. 120 0 207 0 179 -0 4 1 120 21278 - B5V 4 8 7 7 107 - 0. 170 0. 245 0 146 -0 9 400 21428 34 Per B3V 4 4 7 7 204 - 0. 144 . 0. 198 0 095 -o 9 1 500 : HD : Number Other D e s i g . Sp. Type Vo HT Vs i n i C e n t r a l Depth Msp n S/N Comments 4200 H e l l 4387 : Hel 4471 Hel 4481 M g l l 22192 * Per B5Ve s h e l 1 3.88 - - - : - -• - 1 530 NM(Crawford and Barnes 1974); OFC, Hy em. : 22928 6 Per B5IVn 2.91 6. 1 213 • - 0.084 : 0.119 0.069 -1.9 1 550 SB; Vo c o r r e c t e d by 0.2 : 25940 48 Per B4Ve 3 . 32 5.6 205 - 0.125 : 0. 165 0.072 -2.2 1 520 Hy em. NGC 2244 46056 _ _ 08Vn 6 70 2 6 143 0 05G 0 078 0 108 0 033 -4 7 1 180 46106 BOV 6 77 3 1 1 14 0 04 3 0 145 0 218 0 113 -4 2 2 50/60 94* 0 1 16 0 104 0 159 0 104 46149 -- 08 . 5V 6 07 2 2 104 0 068 0 149 0 299 0 1 10 -5 2 2 70/80-46150 -- 05V 5 37 2 3 177 0 140 0 054 0 104 0 024 -5 1 1 200 46202 -- 09V 6 71 3 5 45 0 077 0 198 0 328 0 058 -3 9 1 190 : 46223 -- 04Vf 5 62 1 9 - 0 150 - 0 076 - -5 6 1 140 : 47382 --- BOIII 5 73 2 7 73 . 0 038 0 208 0 297 0 072 -4 6 1 80 : RV Var(Humphreys 1978); Vo c o r r e c t e d by 0.1 RV Var(Humphreys 1978); SB, Vo c o r r e c t e d by 0.2 SB?; V a r i a b l e Magnitude (Johnson 1962) Not i n n e r c l u s t e r member, NM from p o s i t i o n i n Hy-Vo diagram, OFC NGC 2264 47835 15 Mon 07V 4 . 40 2.6 69 O. 125 0.087 0. 210 0.042 -4.7 300 : : C e n t r a l Depth : : : HD Other : Sp. Vo : Hy : V s i n i : : Msp : n : S/N : Comments Number : D e s i g . : Type : : 4200 : 4387 : 4471 : 4481 : : : : : : : : H e l l Hel Hel : M g l l : : : : CYGNUS 0B7 195965 - - BOV 6 23 3 .3 363** 0 033 0 092 0 139 0 021 -4 0 1 120 197345 a c y g A2Ia 1 13 2 1 35* _ 0 071 0 370 _ 1 2000 OFC due to l a r g e d e v i a t i o n from mean Hy-Mv r e l a t i on 198478 55 cy g B3Ia 2 86 1 1 33 — 0 265 0 348 0 194 -7 3 1 500 199216 -- B 111 4 87 1 7 76 0 028 0 230 0 338 0 092 -6 0 1 140 199579 06.5111 5 2 1 1 9 125** 0 133 0 046 0 160 0 027 -5 6 240 Binary(Humphreys 1978); Av=0.75 mag c a l c . from . c e n t r a l depth of X.4430. 203064 68 Cyg 08V 4 13 2 0 362** O 069 0 040 0 105 0 012 -5 5 650 RV Var(Humphreys 1978); SB?, Vo c o r r e c t e d by 0.1 203938 -- BO.51V 4 86 3 0 191 0 027 0 141 0 218 0 048 -4 3 1 130 CEPHEUS 0B3 6 : 216532 — 08V 5 65 3 3 109 0 123 0 144 0 228 0 053 -4 0 1 110 SB; Vo c o r r e c t e d by 0.2 : 216898 08 . 5V 5 59 3 1 50 0 1 16 0 210 0 351 0 064 -4 2 1 100 RV Var(Humphreys 1978); Vo c o r r e c t e d by 0.1 : 217035 -- ' BO. 5V 5 54 3 4 228** 0 055 0 141 0 197 0 064 -3 9 ! 80 B i n a r y , Am=0,sep.=1.9', ( G a r r i s o n 1970); o n l y A comp. used as 1=1.0 : 217086 -- 07n 4 75 2 2 276** 0 105 0 065 0 101 - -5 2 1 90 May be compos i t spectrum ( G a r r i s o n 1970) : 217297 -- B1 . 5V 5 90 3 9 175 0 051 0 189 0 238 0 056 -3 5 1 90 SB; c l o s e d o u b l e ( B H J 1959) Vo c o r r e c t e d by 0.2 : : C e n t r a l Depth : : : : HD : Other Sp. : Vo : Hy : V s i n i : : Msp : n : S/N : Comments Number : D e s i g . : Type : : 4200 : 4387 : 4471 : 4481 : : : : : : : : : : H e l l Hel : Hel : Mgll : : : 217312 : 218066 . . . B0.5V B1.5Vn 5 5 6 1 87 3 4 1 7 1 19 207 0 0 042 025 0 0 170 153 0 0 245 216 0 0 042 041 -4 -2 2 9 1 120 120 SB?; Two l i n e SB(Heard and F e r n i e 1967); Vo c o r r e c t e d by 0.2 SB; Vo c o r r e c t e d by 0.2 : 218323 -- BOIII 5 03 3 1 121 0 075 0 231 0 303 0 066 -4 2 120 : 218342 BOIV 5 47 3 8 58 0 069 0 272 0 372 0 062 -3 6 160 SB; Vo c o r r e c t e d by 0.2 : 218537 -- B2 . 5V 5 73 6 8 2 15 - 0 173 0 234 0 062 -1 4 1 220 SB; p r o b a b l e NM,Am=0.5, sep= 0 . 2 ' ( G a r r i s o n 1970); NM from p o s i t i o n i n Hy-Vo diagram, OFC URSA MAJOR CLUSTER : 95418 f, UMa A 1V 2 46 15 7 40* - - 0 034 0 277 1 2 1 280 RV V a r ( C r a w f o r d and Barnes 1969);Vo c o r r e c t e d by 0.1 : 103287 y UMa AOV 2 44 15 0 200* - - - 0 112 1 1 2 450 : 106591 6 UMa A3V 3 29 16 9 238* - - - 0 109 1 4 2 350 : 112185 6 UMa AOp 1 96 12 8 25* - - 0 037 0 283 0 7 2 800 SB; Vo c o r r e c t e d by 0.2 : 116656 5 UMa A2V 3 19 16 7 65* 44* - - - 0 0 168 153 1 3 2 1000 SB; Vo c o r r e c t e d by 0.2 NM=Non-member S B = S p e c t r o s c o p i c B i n a r y 0 B = 0 c c u l t i n g B i n a r y 0FC=0mitted from c a l i b r a t i o n l = Primary to s e c o n d a r y l i g h t r a t i o *=V s i n i from 4481 M g l l l i n e **=V s i n i from average of 447 1 Hel and 4387 Hel l i n e s T a b l e IV Standard S t a r Data C e n t r a l Depth : : HD : Other Sp. Mv : H7 : V s i n i : : m-M : n : S/N : Comments Number : D e s i g . : Type : : 4200 : 4387 : 4471 : 4481 : : : : : : : : H e l l Hel : Hel : Mg l l : : : : STARS WITH WELL KNOWN DISTANCES : 16970 r Cet • A2V 1 .90 18 8 210* - - - • 0 117 . 5 . 14 4 1300 wt = 0.12 48915 a CMa S i r i us A 1V 1 45 17 5 35* - - - 0 293 5 50 4 1500 wt = 1 .00 60179 a Gem A C a s t o r A 1V 1 35 16 1 29* - - - O 264 5 46 1 1300 wt = 0.17 : 102647 0 Leo Denebola A3V 1 54 18 8 - - - - - 5 50 1 1600 wt = 0.12 : 172167 a Lyr Vega AOV 0 50 17 4 - 10* - - - 0 253 (6 42) 7 1700 (wt = 0.27) : 216956 a Psa Foma1haut A3V 2 03 18 9 121* 0 262 5 00 1 1000 wt = 0.20 ECLIPSING BINARIES : 40183A : 40183B 0 Aur A2IV A2IV 0 0 82 82 17 6 93* -- -0 220 6 13 1 1400 Mv p r i m a r y ±0.20 mag, sec. not used as 1=1.0 : 34364A : 34364B AR Aur B8V B9V 0 1 99 19 14 15 9 3 62* - 0 038 0 033 0 134 5 5 63 50 1 270 Mv Mv pr i m a r y ±0.15 mag secondary ±0.10 mag : 156247A : 156247B U Oph B4V B5V - 1 -0 00 70 7 8 3 4 242 -0 129 0 170 0 069 5 5 32 56 1 140 Mv Mv pri m a r y ±0.10 mag secondary ±0.10 mag : 216014A : 216014B AH Cep BO. 5V B0.5V -4 -4 59 18 3 4 5 1 217 296** 0 027 0 0 091 071 0 0 126 140 0 030 6 6 29 39 1 240 Mv Mv pri m a r y ±0.15 mag secondary ±0.15 mag : 25833A : 25833B AG Per B4V B5V -0 -0 85 35 8 9 7 6 130 0 015 0 193 0 264 0 135 5 5 86 72 1 200 Mv Mv pr i m a r y ±0.15 mag secondary ±0.20 mag : HD : Number : Other : Des1g. Sp. : Type Mv : H T : Vs i ni C e n t r a l Depth : m -M : n : S/N : 4200 . H e l l : 4387 Hel : 4471 : Hel : 4481 : M g l l : 170757A : 170757B : RX Her • B9.5V : A 1V : 0.48 . 1.12 14.3 15.2 43* 70* _ - : 0.025 : 0.092 : 0.053 6 5 06 54 1 190 : 185507A : 185507B a Aql : B3V B3V :-1.80 •-1.47 6.3 6.9 187 120* -0. 176 0. 106 : 0.233 0.067 0.053 5 5 49 56 1 320 : 198846A : 198846B Y Cyg BOV BOV -3 . 45 -3.45 3 . 2 236** 251** -0.066 0.066 0. 127 0.113 -4 66 3 350 VISUAL BINARIES 3369 a Leo A ADS 7654A B7V -0.5 8 . 7 299 - 0.050 0.055 0.056 5 51 2 1500 : 4 161 21 Cas A ADS 624A A2 1 . 7 16 . 7 27* - - - 0.315 5 16 1 270 7710 ADS 1040AB AO 0.8 14.6 197* - - 0.029 0.099 5 80 1 160 10205 T And A ADS 1311A B8IV -1.4 7.0 1 16 - 0.060 0.096 0.111 5 56 1 380 : 16628 33 A r i A ADS 2033A A3V 1 .0 18.5 142* - - - 0. 175 6 02 1 300 : 21447 HR 1046 A ADS 2565A A 1V 2.0 18.3 209* - - - 0. 109 5 00 1 320 22091 7 Tau AB ADS 2616A A3V 0.7 16.6 27* - - - 0.318 6 14 1 250 22951 40 Per A ADS 2699A BO. 5V -3.6 4.0 87 - 0. 244 0. 303 0.077 5 77 2 600 : 29646 HR 1490 A ADS 3379A A2V 1 . 7 17.3 164* - - - 0. 155 5 23 1 200 : 61497 24 Lyn A ADS 6285A A3III -1.5 15.6 255* - - - 0.081 (8 14) 1 500 Comments Mv p r i m a r y ±0.20 mag Mv secondary ±0.15 mag Mv primary ±0.15 mag Mv secondary ±0.15 mag Mv p r i m a r y ±0.15 mag, sec. not used as 1=1 : : : : C e n t r a l Depth : : : : HD. : Other : Sp. Mv : Hy V s i n i : : m-M : n : S/N : Comments Number : D e s i g . : Type : : : : 4200 : 4387 : 4471 : 4481 : : : : : : : H e l l Hel : Hel : Mg l l : : : : 83023 : 7 Leo A : ADS 7448A A 1V 0 8 17 3 138 : - - 0 136 6 13 3 150 87901 ir And A ADS 513A B5IV - 1 3 6 7 66 - 0 140 0 200 0 115 5 27 1 900 127304 ADS 9288A B9p L0 7 15 8 20* - - 0 036 0 273 (7 46) 1 300 141003 p Ser A ADS 9778A A2IV 0 8 16 3 2 12* - - - 0 120 6 02 4 290 142742 ADS 9838A A3 2 6 18 0 101* - - - 0 256 (4 32) 1 250 : 149303 ADS 10105A A 1 2 0 17 3 250* - - - 0 094 4 92 1 310 : 154660 ADS 10347A A2 2 6 14 3 259* - - - 0 103 (3 77) 1 280 : 170073 39 Dra AB ADS 11336AB A 1 V 1 6 18 7 219* - - - 0 122 5 42 1 400 : 200120 59 Cyg A ADS 1452GA B3e -3 8 4 4 - - 0 085 0 1 14 0 025 6 25 1 400 : 205021 0 Cep A ADS 15032A B2111 -2 5 4 0 -28 0.022 0 291 0 366 0 123 4 65 1 1200 : 216916 16 Lac A ADS 16381A B2IV -2 9 4 2 66** - 0 297 0 324 - 5 20 1 360 : 221253 AR Cas AB ADS 16795AB B3V - 1 7 6 3 188 0 187 0 244 0 078 5 40 1 500 : 32 CHAPTER 3 : DATA REDUCTION A l l R e t i c o n s p e c t r a were r e c o r d e d on m a g n e t i c t a p e and r e d u c e d w i t h RETICENT, a command l a n g u a g e d e v e l o p e d a t UBC f o r t h e m a n i p u l a t i o n o f o n e - d i m e n s i o n a l d i g i t a l d a t a ( P r i t c h e t , M o c h a n a c k i , and Yang 1982). The r e d u c t i o n s e q u e n c e was a s f o l l o w s . A b a s e l i n e ( d a r k ) was s u b t r a c t e d from e a c h d a t a frame and t h e r e s u l t a n t d i v i d e d by a f l a t f i e l d frame ( l a m p ) . The. l a t t e r was done t o remove t h e R e t i c o n d i o d e - t o - d i o d e ' r e s p o n s e p a t t e r n . T h i s t y p i c a l l y r e s u l t e d i n s p e c t r a o f t h e form shown i n f i g u r e s 2 and 3. The s l o p e of t h e c o n t i n u u m i s p r i n c i p l y due t o t h e R e t i c o n ' s r e s p o n s e t o t h e lamp u s e d t o o b t a i n t h e f l a t f i e l d . A t h i r d o r d e r p o l y n o m i a l was t h e n f i t t e d t o e a c h s p e c t r u m i n t h e XX4150-4550 r e g i o n , s p a n n i n g H 7 , t o d e t e r m i n e t h e c o n t i n u u m l e v e l ( f i g u r e s 4 and 5 ) . Due t o t h e u n c o m p l i c a t e d shape o f t h e c o n t i n u u m o n l y 2 o r 3 f i t s , p e r f o r m e d i n t e r a c t i v e l y , were n e c e s s a r y t o a d e q u a t e l y d e t e r m i n e t h e c o n t i n u u m l e v e l . The s p e c t r a were t h e n n o r m a l i z e d t o t h i s l e v e l and t h e f i n a l t r a c i n g s expanded t o 170 t i m e s t h e o r i g i n a l 33 d i s p e r s i o n ( f i g u r e s 6 and 7 ) . None o f t h e s p e c t r a have been smoothed. The d i s p e r s i o n s were f o u n d from F e / A r c o m p a r i s o n l i n e s p e c t r a w h i c h were t a k e n d u r i n g e a c h n i g h t s ' o b s e r v a t i o n s . The p o s i t i o n s o f s e l e c t e d l i n e s were f o u n d by f i t t i n g a p a r a b o l a t o t h e l o g a r i t h m of t h e l i n e p r o f i l e s . A l l d i s p e r s i o n r e l a t i o n s f o u n d were t h i r d o r d e r p o l y n o m i a l s w i t h t h e mean sigma ( l a ) l e v e l e q u a l t o 0.037A. The H 7 wing p r o f i l e s were drawn by hand i n a c o n s i s t a n t manner w i t h s p e c i a l e m p h a s i s p l a c e d on k e e p i n g t h e p r o f i l e s s y m m e t r i c a l a b o u t t h e l i n e c e n t e r s . The l i n e a r e a s were measured w i t h a p l a n i m e t e r . F o l l o w i n g P e t r i e (1965) t h e O i l l i n e n e a r X4349 was c o m p e n s a t e d f o r i n t h e B s t a r s but no a c c o u n t was made f o r t h e H e l l l i n e a t X4339 i n t h e 0 s t a r s . A l t h o u g h t h i s l a t t e r b l e n d c o u l d be seen i n some of t h e 0 s t a r s , c o r r e c t i n g f o r i t would have p r o v e n a d i f f i c u l t t a s k due t o i t s c l o s e p r o x i m i t y t o H 7 . The o n l y d e v i a t i o n t o t h e above p r o c e d u r e was w i t h t h e O c t o b e r d a t a where i t was n e c e s s a r y t o f i l t e r t h e lamps t o 49% of t h e N y q u i s t f r e q u e n c y p r i o r t o t h e d i v i s i o n i n t o t h e s t e l l a r s p e c t r a l f r a m e s . T h i s was p e r f o r m e d t o remove a f i x e d l i n e p a t t e r n f r o m t h e p r o c e s s e d d a t a w h i c h o r i g i n a t e d i n t h e lamps. To d e t e r m i n e whether t h i s had any s u b s e q u e n t e f f e c t on t h e EW m e a s u r e s , a number o f t h e same o b j e c t s were r e o b s e r v e d i n December and t h e H 7 EWs d e t e r m i n e d . No s i g n i f i c a n t s y s t e m a t i c e f f e c t s a r e p r e s e n t and, a s s u c h , no c o r r e c t i o n s were a p p l i e d t o t h e O c t o b e r d a t a . A number o f o b s e r v e d c l u s t e r c a n d i d a t e s have n o t been u s e d flOC U N I T S U_o gain) I—H hh oo I—i m DO § I—1 Hh CD P-CD (/) Q-> CD • o rt CD cr CD 3 CD C/l & c+ -t P O rt P-O 3 Cu Cu P-P" (/) P-o cr CO cn J* - j 0___ ro co co CD cn cn co —i ro • cn CD O -o l - l X m ro o o CO o o He I 4026 — He I 4144 — Hel4471-H e l 4387 — M g II 4481 «C9 5 ro CO Ol CO CO M to •6 CO cn o o c "D CO I cn cn co I CD CD < < o I « CO HOC U N I T S (Hi gain) 9 C PDC UNITS (Hi gain) r-o ro to tn It INTENSITY 6 £ 40 i n t h e c o n s t r u c t i o n of t h e c a l i b r a t i o n . T h e s e i n c l u d e non-members f o u n d by o t h e r a u t h o r s , s t a r s where t h e e m i s s i o n i n H 7 was t o o s e v e r e t o c o r r e c t , and s t a r s t h a t d e v i a t e d s t r o n g l y f r o m t h e i r r e s p e c t i v e c l u s t e r s e q u e n c e s i n t h e H 7 - V 0 p l a n e . T h i s l a t t e r c a s e i n c l u d e s two p e c u l i a r s t a r s (HD 37022, 06p, O r i o n j OB1; HD 23862, B8pV, P l e i a d e s ) . The s t a r s HD 47382 (NGC 2 2 4 4 ) , HD 218537 (Cep OB3), and HD 23950 ( P l e i a d e s ) a l l c l a s s i f i e d a s non-members o r p o s s i b l e non-members i n t h e l i t e r a t u r e , d e v i a t e s i g n i f i c a n t l y from t h e i r r e s p e c t i v e c l u s t e r s e q u e n c e s and, a s s u c h , a r e c o n f i r m e d h e r e as non-members. U n f o r t u n a t e l y HD 22192 (a P e r ) , c l a s s i f i e d a s a non-member by C r a w f o r d and B a r n e s (1974) and a p o s s i b l e non-member by Abt (1978) has e m i s s i o n a t H 7 and no EW v a l u e c o u l d be o b t a i n e d . F i g u r e 8 shows t h e e s t i m a t e d - ^ i n t e r n a l a c c u r a c y o f t h e W(H7) measures as a f u n c t i o n o f t h e p o i n t t o p o i n t s i g n a l - t o - n o i s e r a t i o o f t h e s p e c t r a . The d a t a come from s t a r s where 2 o r more o b s e r v a t i o n s were made. I t i s c l e a r t h a t t h e i n t e r n a l a c c u r a c y i s a f u n c t i o n of s i g n a l s t r e n g t h and t h a t f o r a S/N of >150:1 i t i s 4% o r b e t t e r . The v e r y b e s t p h o t o g r a p h i c s p e c t r a have a S/N of a p r r o x i m a t e l y 100:1 and a r e t y p i c a l l y much l e s s t h a n t h i s . The r e s u l t i n g i n t e r n a l a c c u r a c y i s u s u a l l y i n t h e 10% o r worse r a n g e . EQUIVALENT WIDTH COMPARISONS Most a u t h o r s p u b l i s h EW v a l u e s w i t h o u t any r e f e r e n c e t o a s t a n d a r d i z e d t e c h n i q u e u s e d t o d e t e r m i n e t h e c o n t i n u u m l e v e l s and l i n e b l e n d s . T h i s i s p r o b a b l y due t o t h e f a c t t h a t s u c h a t e c h n i q u e i s d i f f i c u l t t o d e f i n e due t o t h e i n d i v i d u a l FIG. 8. The variation of the internal accuracy of the equivalent widths of H 7 as a function of signal-to-noise. 42 c h a r a c t e r i s t i c s o f e a c h s u r v e y ( d e t e c t o r s , d i s p e r s i o n s , s i g n a l s t r e n g t h s ) . As a r e s u l t , t h e EW measures o f one a u t h o r may s y s t e m a t i c a l l y d i f f e r from a n o t h e r . T h i s c a n be e s p e c i a l l y t r u e when d a t a of d i f f e r e n t d i s p e r s i o n s a r e compared. The h i g h S/N d a t a i n t h e p r e s e n t s t u d y a l l o w s one t o assume t h a t e s s e n t i a l l y a l l t h e f e a t u r e s seen i n t h e s p e c t r a a r e r e a l and n o t due t o n o i s e . T h i s r e d u c e s t h e r a t h e r i n t e r p r e t i v e n a t u r e o f c o n t i n u u m and l i n e wing p l a c e m e n t i n c o m p a r i s o n t o p h o t o g r a p h i c t e c h n i q u e s . C o m p a r i s o n s o f t h e EW measures from t h i s s t u d y and t h o s e e m p l o y i n g p h o t o g r a p h i c p l a t e s and p h o t o e l e c t r i c s c a n n e r s a r e shown i n f i g u r e s 9-13 ( S t o c k 1956, p h o t o e l e c t r i c , o b j e c t i v e -p r i s m s p e c t r a ; B l a n c h a r d e t a l . 1974, p h o t o e l e c t r i c , r e c i p r o c a l d i s p e r s i o n = 4.1 t o 7.1 %/mm; Beer 1961, p h o t o g r a p h i c , o r e c i p r o c a l d i s p e r s i o n = 29 and 49 A/mm; Crampton e t a l . 1974 ( P e t r i e ' s m e a s u r e s ) , p h o t o g r a p h i c , r e c i p r o c a l d i s p e r s i o n = 30 o and 51 A/mm; B a l o n a 1975, p h o t o g r a p h i c , r e c i p r o c a l d i s p e r s i o n = o 49 (most) and 29 A/mm). The s o l i d l i n e i n a l l c a s e s i s of u n i t g r a d i e n t . The most c o m p l e t e c o m p a r i s o n i s w i t h P e t r i e , where t h e r e a r e 98 s t a r s i n common. The d a s h e d l i n e i n f i g u r e 12 r e p r e s e n t s a l i n e a r l e a s t s q u a r e s f i t t o t h e d a t a , and i s o f t h e form Wp = 0.16 + 0.98Wm. The agreement i s e x c e l l e n t , w i t h t h e mean r e s i d u a l between t h e two s e t s o f measures b e i n g l e s s t h a n 2%. From f i g u r e s 9 and 10 i t c a n be seen t h a t t h e EW v a l u e s of FIG. 9. Comparison of the H7 equivalent width values of Stock (1956) with those of the present study. FIG. 10. Comparison of the HY equivalent width values of Blanchard et al. (1974) with those of the present study. k5 FIG. 11. Comparison of the H7 equivalent width values of Beer (1961) with those of the present study. U(HyJ (fU FIG. 12. Comparison i f the H7 equivalent width values o f P e t r i e (1974) with those of the present study. The dashed l i n e represents the best l i n e a r l e a s t squares f i t to the data. B G 0 0 0 0 0 0 UU+yJ IflJ a ftJUvard FIG. 13. Comparison of the H7 equivalent width values of Balona (1975) with those of the present study. 48 S t o c k and B l a n c h a r d e t a l . , b o t h p h o t o e l e c t r i c , a r e a p p r o x i m a t e l y 10% g r e a t e r t h a n i n t h e p r e s e n t s t u d y . The two s t u d i e s a g r e e w e l l w i t h one a n o t h e r . S t o c k a l s o f o u n d t h a t h i s v a l u e s were s y s t e m a t i c a l l y l a r g e r t h a n t h e v a l u e s o f G u n t h e r (1933) and P e t r i e (1953) ( b o t h p h o t o g r a p h i c ) , i n t h e same s e n s e as a b o v e . The agreement o f t h e m e a s u r e s o f B a l o n a and B e e r w i t h t h e p r e s e n t s t u d y a p p e a r s good, a l t h o u g h t h e r e a r e a l a c k of c o m p a r i s o n s t a r s . D i d e l o n (1982) has f o u n d , f r o m a s t u d y of p u b l i s h e d EW v a l u e s o f s p e c t r a l l i n e s i n B - t y p e s t a r s , t h a t t h e EWs s y s t e m a t i c a l l y i n c r e a s e as t h e r e c i p r o c a l d i s p e r s i o n s d e c r e a s e . W h i l e t h i s may e x p l a i n B l a n c h a r d ' s v a l u e s b e i n g s y s t e m a t i c a l l y l a r g e r t h a n t h o s e o f t h e p r e s e n t s t u d y i t c e r t a i n l y d o e s n o t e x p l a i n S t o c k ' s v a l u e s , as t h e s e were d e r i v e d from o b j e c t i v e p r i s m s p e c t r a . A more l i k e l y e x p l a n a t i o n f o r t h e s y s t e m a t i c d i f f e r e n c e s seen i s t h a t b o t h B l a n c h a r d e t a l . and S t o c k d i d no t r e c t i f y t h e i r s p e c t r a when d e t e r m i n i n g t h e W ( H Y ) ; B e e r , B a l o n a , and P e t r i e a l l d i d . B l a n c h a r d u s e d t h e a p p r o x i m a t i o n of d i v i d i n g t h e l i n e a r e a by t h e c o n t i n u u m i n t e n s i t y a t t h e l i n e ' s c e n t r a l d e p t h and S t o c k , e m p l o y i n g an e f f e c t i v e s l i t w i d t h o f o between 35 and 53 A, f o u n d EWs a s a f u n c t i o n o f t h e c e n t r a l d e p t h o f H 7 . An i n t e r e s t i n g a s p e c t of f i g u r e 12 i s t h e a p p a r e n t i n c r e a s e o i n s c a t t e r f o r EW v a l u e s >13 A. T h e s e p o i n t s r e p r e s e n t l a t e B and e a r l y A - t y p e s t a r s w i t h t h e l a r g e s t d i s c r e p a n c i e s b e i n g a p p r o x i m a t e l y 20%. T h i s e f f e c t h a s a l s o been n o t e d by B l a n c h a r d e t a l . (1974) when c o m p a r i n g v a r i o u s a u t h o r s ' H 7 EW v a l u e s . The i n c r e a s e d s c a t t e r i s most l i k e l y due t o t h e c o n t i n u u m 49 p l a c e m e n t and t h e r e s u l t a n t s i z e and shape o f t h e l i n e w i n g s . The h y d r o g e n Balmer l i n e s become v e r y wide and deep f o r t h e e a r l y A - t y p e s t a r s and t h e c o n t i n u u m p l a c e m e n t c a n be d i f f i c u l t f o r l o w e r S/N s p e c t r a . A l s o , p h o t o g r a p h i c p l a t e c a l i b r a t i o n e r r o r s c an become s e r i o u s f o r deep l i n e s ( P e t r i e and M a u n s e l l 1950). R e t i c o n s p e c t r a w i l l n o t s u f f e r f r o m t h i s l a t t e r p r o b l e m b e c a u s e t h e R e t i c o n i s a l i n e a r d e v i c e . Thus, t h e l a r g e r s c a t t e r a t l a r g e EWs i s n o t t o t a l l y u n e x p e c t e d , a s p h o t o g r a p h i c and R e t i c o n s p e c t r a a r e b e i n g compared. However, t h i s i s somewhat d i s t u r b i n g a s t h e e a r l y A - t y p e s t a r s a r e i m p o r t a n t i n s e t t i n g t h e z e r o p o i n t o f t h e c a l i b r a t i o n . I t i s f e l t , on t h e o t h e r hand, t h a t w i t h t h e h i g h S/N s p e c t r a u s e d i n t h e p r e s e n t s t u d y , t h a t t h e c o n t i n u u m p l a c e m e n t f o r t h e A - t y p e s t a r s , w h i l e n o t b e i n g as c e r t a i n a s f o r t h e 0 and B s t a r s , due t o t h e wide l i n e w i n g s , i s none t h e l e s s q u i t e c o n s i s t a n t ; and t h a t t h e p r e s e n t l a t e B and e a r l y A - t y p e s t a r EWs a r e s u p e r i o r t o p h o t o g r a p h i c v a l u e s . An a t t e m p t t o d e m o n s t r a t e t h i s i s shown i n f i g u r e 14. The p o i n t s r e p r e s e n t P l e i a d e s members l a t e r t h a n B7 i n t h e W ( H 7)-Vo p l a n e . C r o s s e s show t h e d a t a from t h e p r e s e n t s t u d y , w h i l e c i r c l e s a r e P e t r i e ' s (1965) d a t a f o r t h e same s t a r s . I n b o t h c a s e s t h e v i s u a l m a g n i t u d e s c o r r e c t e d f o r r e d d e n i n g have been t a k e n f r o m t h i s s t u d y i n o r d e r t o i s o l a t e t h e e f f e c t o f t h e d i f f e r e n t EWs. I t i s e v i d e n t t h a t t h e p r e s e n t H 7 EW v a l u e s r e s u l t i n a t i g h t e r s e q u e n c e . The p o i n t s marked SB r e p r e s e n t t h e s t a r s HD 24076 and HD 23432 w h i c h a r e f o u n d t o be p o s s i b l e s p e c t r o s c o p i c b i n a r i e s f r o m t h e i r s p e c t r a . The a p p a r e n t p o s i t i o n s s l i g h t l y above ( b r i g h t e r t h a n ) t h e c l u s t e r s e q u e n c e FIG. 14. The P l e i a d e s c l u s t e r sequence f o r observed s t a r s l a t e r than s p e c t r a l type B7. C i r c l e s represent Petrie»s (1965) sequence, X's the sequence from the present study. Note the b r i g h t e r r e l a t i v e p o s i t i o n s o f the two p o s s i b l e s p e c t r o s c o p i c b i n a r i e s . a l s o p o i n t s t o t h e i r p o s s i b l e b i n a r y n a t u r e . 52 CHAPTER 4 : THE CALIBRATION The c a l i b r a t i o n p r o c e d u r e i s e s s e n t i a l l y t h e same as t h a t o f P e t r i e ( 1 9 6 5 ) . The e x c e p t i o n s a r e t h a t t h e z e r o p o i n t s t a r s n o t o n l y z e r o t h e c a l i b r a t i o n but a s s i s t i n d e f i n i n g t h e shape of t h e r e l a t i o n . A l s o , t h e e c l i p s i n g b i n a r y s e c o n d a r i e s a s w e l l a s t h e p r i m a r i e s have been u s e d i n z e r o i n g t h e r e l a t i o n . CLUSTER AND ASSOCIATION MEMBERS The shape o f t'he r e l a t i o n i s f o u n d by f i t t i n g t h e v a r i o u s c l u s t e r s e q u e n c e s i n t h e W(H7)-Vo p l a n e a l o n g a common c u r v e , u s i n g t h e P l e i a d e s a s t h e a n c h o r c l u s t e r . F i r s t , an e m p i r i c a l c u r v e i s f i t t e d t o e a c h s e p a r a t e c l u s t e r s e q u e n c e , and t h e s e a r e t h e n f i t t e d t o g e t h e r by s l i d i n g t h e s e q u e n c e s i n m a g n i t u d e u n t i l t h e y o v e r l a y one a n o t h e r . I n i t i a l l y , t h e UMa c l u s t e r and a Per s e q u e n c e s a r e f i t t e d t o t h e P l e i a d e s s e q u e n c e , t h e n O r i o n 0B1, Cepheus OB3, NGC 2244, NGC 2264, a n d Cygnus OB7 a r e f i t t e d , i n t h a t o r d e r , e x t e n d i n g t h e r e l a t i o n t o e a r l i e r s p e c t r a l t y p e s . A f t e r a l l t h e c l u s t e r s have been f i t t e d , t h e r e l a t i o n e x t e n d s f r o m about 05 t o A2. As m e n t i o n e d p r e v i o u s l y , 6 s p e c t r o s c o p i c b i n a r i e s w i t h 53 known s e c o n d a r y - t o - p r i m a r y l i g h t r a t i o s (1) a r e i n c l u d e d w i t h t h e o b s e r v e d members o f t h e O r i o n 0B1 a s s o c i a t i o n . F o u r o f t h e s e s e c o n d a r i e s have been u s e d i n t h e c a l i b r a t i o n . A f t e r P e t r i e (1953) t h e EWs o f t h e s e s e c o n d a r i e s were f o u n d as f o l l o w s . A p r e l i m i n a r y f i t o f t h e form Vo = a + b ( l o g W ( H 7 ) ) i n t h e W ( H 7)-Vo p l a n e was made t o t h e c l u s t e r s e q u e n c e minus t h e 4 s p e c t r o s c o p i c b i n a r i e s w i t h ( 1 ) ^ 0 . 3 6 . From t h i s f i t AW was f o u n d f o r a l l b i n a r i e s and u s i n g t h e e q u a t i o n s on page 20 t h e c o r r e c t e d EWs o f t h e 4 p r i m a r i e s were t h e n f o u n d a l o n g w i t h t h e H 7 EWs o f t h e 4 s e c o n d a r i e s . T h e s e 8 v a l u e s were t h e n added t o t h e O r i o n OB1 s e q u e n c e and an e m p i r i c a l c u r v e f i t t e d t o t h e d a t a . T h i s f i t was e s s e n t i a l l y t h e same as t h e p r e l i m i n a r y l o g f i t and was u s e d i n f i t t i n g t h e s e q u e n c e t o t h e P l e i a d e s and t h e a P e r s e i a s s o c i a t i o n . BC f i t l o g c u r v e s t o a l l t h e c l u s t e r s e q u e n c e s i n d e f i n i n g t h e shape o f t h e i r r e l a t i o n and t h e i r f i n a l c a l i b r a t i o n i s g i v e n as a l o g f u n c t i o n . W h i l e l o g c u r v e s f i t t h e p r e s e n t d a t a o r e a s o n a b l y w e l l f o r EWs l e s s t h a n 7 A, i t i s f o u n d t h e y do n o t do so f o r t h e r e s t o f t h e r e l a t i o n . T hus, l o g f i t s were abandoned i n f a v o r o f e m p i r i c a l o n e s , e s p e c i a l l y s i n c e t h e l o g f i t t o t h e P l e i a d e s , t h e r e l a t i o n ' s a n c h o r c l u s t e r , i s p a r t i c u l a r y p o o r . A f t e r e a c h c l u s t e r s e q u e n c e was f i t t e d t o t h e p r e c e d i n g c l u s t e r o r c l u s t e r s , t h e r e s i d u a l s a b o u t t h e mean d e r i v e d c u r v e were examined t o d e t e r m i n e what s p e c t r a l t y p e c o r r e c t i o n s 54 ( P e t r i e 1965), i f any, would be n e c e s s a r y . The p r o c e s s was r e p e a t e d f o r t h e r e l a t i o n as a whole a f t e r a l l t h e c l u s t e r s e q u e n c e s had been f i t t e d t o g e t h e r . No s i g n i f i c a n t r e s i d u a l s c o r r e l a t e d w i t h s p e c t r a l t y p e were f o u n d f o r l u m i n o s i t y c l a s s e s I I - V ( f i g u r e 15) and, a s s u c h , none a r e n e e ded when u s i n g t h e p r e s e n t c a l i b r a t i o n . I t s h o u l d be n o t e d t h a t t h e mean r e s i d u a l (+0.16 mag.) f o u n d f o r s p e c t r a l t y p e s 04-07 i s b a s e d on o n l y 5 s t a r s and, as s u c h , i s p r o b a b l y n o t s i g n i f i c a n t . T h i s d i f f e r s f r o m P e t r i e (1950,1956,1965), who f o u n d t h e need f o r s p e c t r a l t y p e c o r r e c t i o n s , as w e l l a s BC, who e s s e n t i a l l y d e r i v e d a s e p a r a t e r e l a t i o n f o r e a c h s p e c t r a l t y p e f r o m 06-A1. However, e v i d e n c e f o r c o r r e c t i o n s t o l a t e B and e a r l y A - t y p e s u p e r g i a n t s , i n t h e same s e n s e a s P e t r i e , and BC, were f o u n d and w i l l be d i s c u s s e d l a t e r . F i g u r e 16 shows t h e W(H7)-Vo c l u s t e r s e q u e n c e . ZERO POINT STARS As m e n t i o n e d p r e v i o u s l y , t h e c a l i b r a t i o n has been z e r o e d w i t h t h r e e g r o u p s o f s t a r s . (1) S t a r s w i t h w e l l known t r i g o n o m e t r i c p a r a l l a x e s and hence r e l i a b l e a b s o l u t e m a g n i t u d e s (5 s t a r s ) (2) E c l i p s i n g b i n a r i e s w i t h w e l l d e t e r m i n e d d i m e n s i o n s (8 p r i m a r i e s , 6 s e c o n d a r i e s ) (3) V i s u a l b i n a r i e s where t h e a b s o l u t e m a g n i t u d e o f t h e p r i m a r i e s has been d e t e r m i n e d by f i t t i n g t h e s e c o n d a r i e s t o t h e ZAMS (18 s t a r s ) 55 z: 2 > u ZD C J co a Q CO 3 -3 -0.6 f Spectral Type FIG. 15. P o i n t s represent the mean r e s i d u a l s (0-C) i n magnitude about the f i n a l c a l i b r a t i o n as a f u n c t i o n o f s p e c t r a l type. The v e r t i c a l l i n e s give the mean d i s p e r s i o n about the c a l i b r a t i o n f o r the same s p e c t r a l bins as the p o i n t s . The mean d i s p e r s i o n f o r the e n t i r e c a l i b r a t i o n i s +0.28 magnitudes. HD 197345 A2 la 0 * 0 DO O 0 ~ (9 o C35) ° 0 1 1 1 1 1 1 1 1 1 2 4 6 8 10 12 14 16 18 U(Hy) (fl) FIG. 16. The W(H7)-Vo sequence f o r a l l c l u s t e r members used i n the c a l i b r a t i o n . Note the p o s i t i o n of HD 197345. The s t a r has not been i n c l u d e d i n the present c a l i b r a t i o n . 57 F i g u r e 17 shows the members from a l l t h r e e groups used i n the c a l i b r a t i o n . I t s h o u l d be noted tha t the s c a t t e r in the z e r o p o i n t s t a r s has been s i g n i f i c a n t l y reduced from tha t of P e t r i e (1965), e s p e c i a l l y f o r the B s t a r s . Vega (a L y r ) has been o m i t t e d from the t r i g o n o m e t r i c group as i t i s a p p r o x i m a t e l y one magnitude too b r i g h t f o r i t s EW as compared to the o ther t r i g o n o m e t r i c s t a r s . A p o s s i b l e e x p l a n a t i o n i s t h a t Vega i s a c l o s e b i n a r y system, a h y p o t h e s i s suggested by v a r i o u s a u t h o r s over the y e a r s . With r e g a r d to z e r o i n g the r e l a t i o n , the s t a r s i n t h i s group have been weighted a c c o r d i n g to the i n v e r s e of the u n c e r t a i n t y i n t h e i r t r i g o n o m e t r i c p a r a l l a x e s . The w e i g h t i n g f a c t o r s are l i s t e d i n column 15 of t a b l e I I I . The W(H7) f o r the p r i m a r y and secondary components of the e c l i p s i n g b i n a r i e s were de termined u t i l i z i n g t h e i r s e c o n d a r y - t o -p r i m a r y l i g h t r a t i o s . A p r e l i m i n a r y e m p i r i c a l f i t to the t r i g o n o m e t r i c s t a r s and v i s u a l b i n a r y A components was used to determine AW for each system. The s e c o n d a r i e s were i n c l u d e d in the c a l i b r a t i o n o n l y i f the l i g h t r a t i o s were between 0.5 and 1.0. A l l components were a s s i g n e d equa l w e i g h t . P e t r i e (1965) exc luded |3 Ser A from h i s group of v i s u a l b i n a r i e s due to an i n d i c a t i o n from the H 7 p r o f i l e tha t the s t a r was a two-spectrum b i n a r y . No such i n d i c a t i o n i s found from a number of R e t i c o n s p e c t r a of the s t a r and as such /3 Ser A has been i n c l u d e d . A l s o , P e t r i e e x c l u d e d 0 Cep A due to i t s l a r g e r e s i d u a l from the mean zero p o i n t c o r r e c t i o n of the v i s u a l b i n a r y group and q u e s t i o n e d the b i n a r y nature of the system. FIG. 17. The W(HT)-MV diagram f o r a l l the s t a r s used to zero the c a l i b r a t i o n . C i r c l e s = t r i g o n o m e t r i c s t a r s ; t r i a n g l e s = e c l i p s i n g b i n a r i e s (primaries and secondaries); diamonds=primary components o f v i s u a l b i n a r i e s . qo 59 W h i l e t h e r e s i d u a l f o u n d h e r e i s l a r g e (0.88 mag.), i t i s n o t as l a r g e as P e t r i e f o u n d and has been i n c l u d e d . B o t h t h e s e s t a r s a r e shown i n f i g u r e 17. 24 L y n , ADS 9228, ADS 9838, and ADS 10347 have a l l been e x c l u d e d f r o m t h e p r e s e n t c a l i b r a t i o n a s t h e y d e v i a t e s i g n i f i c a n t l y f r o m t h e mean r e l a t i o n f o r t h e z e r o p o i n t s t a r s . The s c a t t e r i n a b s o l u t e m a g n i t u d e f o r t h e v i s u a l o b i n a r y A - t y p e s t a r s ( f i g u r e 17, W(H7)>16 A) i s p r o b a b l y due t o t h e u n c e r t a i n t y i n t h e d e t e r m i n e d a b s o l u t e m a g n i t u d e s a s t h e s p e c t r a l t y p e s o f most o f t h e s e s e c o n d a r i e s a r e n o t p r e c i s e l y known. A l l s t a r s i n t h i s g r o u p have been a s s i g n e d e q u a l w e i g h t . The z e r o p o i n t c o r r e c t i o n due t o a s t a r f r o m any o f t h e above g r o u p s i s d e t e r m i n e d f r o m t h e f i t o f t h e s t a r t o t h e mean r e l a t i o n f o r t h e c l u s t e r s e q u e n c e s and i s l i s t e d i n column 12 o f t a b l e I I I . B e c a u s e a l l t h e c l u s t e r s were f i t t e d r e l a t i v e t o t h e P l e i a d e s , t h e z e r o p o i n t c o r r e c t i o n f a c t o r i s t h e d e r i v e d d i s t a n c e modulus o f t h e P l e i a d e s . The mean c o r r e c t i o n s due t o t h e t h r e e g r o u p s w i t h t h e i r a s s o c i a t e d p r o b a b l e e r r o r s (p.e.) a r e l i s t e d b e l o w . (1) T r i g . S t a r s : 5.41 ± 0.13 (2) E c l i p s i n g B i n a r i e s : 5.69 ± 0.30 (3) V i s u a l B i n a r i e s : 5.53 ± 0.32 The i n t e r a g r e e m e n t between t h e t h r e e g r o u p s i s good and t h e mean v a l u e , w e i g h t i n g i n v e r s e l y a s t h e p r o b a b l e e r r o r i s 60 5.50 ± 0.21 T h i s c o r r e c t i o n i s a p p l i e d t o t h e c l u s t e r s e q u e n c e s t a r s and t h e d a t a i s r e b i n n e d t o i n c l u d e t h e z e r o p o i n t s t a r s . The r e s u l t i n g r e l a t i o n i s e s s e n t i a l l y unchanged from t h e c l u s t e r s e q u e n c e e x c e p t f o r t h e 5.50 m a g n i t u d e s h i f t . The f i n a l c a l i b r a t i o n i s shown i n g r a p h i c a l form i n f i g u r e s 18 and 19. The b i n n e d p o i n t s shown i n f i g u r e 19 a r e l i s t e d i n t a b l e V. F o r c o m p a r i s o n w i t h o t h e r c a l i b r a t i o n s i t i s u s e f u l t o know t h e i n t r i n s i c s t e l l a r l u m i n o s i t y a s a f u n c t i o n o f MK s p e c t r a l t y p e . T a b l e VI l i s t s j u s t t h i s . The mean Hy EWs p e r s p e c t r a l t y p e were t a k e n f r o m BC, where t h e W (H7) of 1932 OB s t a r s were u s e d t o c a l c u l a t e t h e means. The a b s o l u t e m a g n i t u d e s l i s t e d i n t a b l e VI were f o u n d by a p p l i n g t h e BC means t o t h e p r e s e n t c a l i b r a t i o n . T h i s t a b u l a t i o n s h o u l d o n l y be u s e d f o r c a l i b r a t i o n c o m p a r i s o n s , as t h e l u m i n o s i t i e s l i s t e d a r e p r o b a b l y n o t as a c c u r a t e a s ones d e t e r m i n e d from t h e p r e s e n t H 7 EWs a l o n e ( f i g u r e 19, t a b l e V ) . T a b l e V I I g i v e s t h e c l u s t e r m o d u l i d e r i v e d f r o m t h e f i t t i n g p r o c e d u r e when t h e z e r o p o i n t c o r r e c t i o n i s a p p l i e d (column 2 ) . Column 3 g i v e s t h e mean d i s t a n c e m o d u l i o f t h e c l u s t e r s and t h e a s s o c i a t i o n s d e r i v e d from t h e f i n a l c a l i b r a t i o n . The p r o b a b l e e r r o r s f o r an i n d i v i d u a l s t a r a r e a l s o g i v e n . T h e s e v a l u e s a g r e e c l o s e l y w i t h t h o s e i n column 2 i n d i c a t i n g t h a t t h e e m p i r i c a l f i t s , u s e d t o f i t t h e c l u s t e r s e q u e n c e s t o g e t h e r , r e p r e s e n t t h e d a t a w e l l . In a d d i t i o n , r e c e n t d e t e r m i n a t i o n s o f t h e c l u s t e r m o d u l i w h i c h were o b t a i n e d from t h e l i t e r a t u r e a r e l i s t e d . The c o m p a r i s o n s a r e good i n a l l c a s e s b u t one, Cyg OB7. i 1 1 — i 1 1 —r < i i 1— 1 u 1 1 - » — 1 — 2 4 6 8 10 12 14 16 18 20 U(Hy) (flJ FIG. 18. The f i n a l W(H7)-Mv c a l i b r a t i o n . C i r c l e s denote c l u s t e r members, crosses zero p o i n t s t a r s . The mean r e l a t i o n shown r e s u l t s from b i n n i n g the data i n t o 10 groups (see t a b l e 5, f i g u r e 19). 62 T a b l e V E q u i v a l e n t Width V a l u e s and A b s o l u t e Magnitudes W(H 7) : Mv : n 1 .70 : -5.97. : 8 2.31 : -5.09 : 7 3.32 : -3.90 : 16 4.37 . -3.29 : 14 6.28 -1 .76 1 5 7.95 -0.82 15 11.03 • : 0.30 : 6 14.64 : 0.99 i 1 0 16.72 : 1 .34 : 1 3 18.50 : 1 .56 : 8 T a b l e VI A b s o l u t e Magnitudes of MK S p e c t r a l Types K type : V : I I I 05 : -5.3 06 : -5.3 07 : -4.9 08 : -4.8 09 : -4.4 : -5.0 BO : -3.6 : -4.3 B1 : -3.2 : -4.1 B2 : -2.5 : -3.6 B3 : -1.9 : -2.9 B4 -1.6 B5 : -1.2 -2.0 B6 : -0.8 j -1.5 B7 : -0.4 : -1 .2 B8 ': 0.0 : -0.9 B9 : 0.5 : -0.4 AO i 1.0 : 0.0 A1 : 1.2 : A2 : 1.3 :' A3 : 1.2 : 65 Table V I I C l u s t e r and A s s o c i a t i o n D i s t a n c e M o d u l i C l u s t e r or Assoc i a t i o n : D i s t a n c e mod. : from f i t t i n g : p r o c e d u r e : D i s t a n c e mod. : from : c a l i b r a t i o n : n : L i t e r a t u r e P l e i a d e s : 5.50 : 5.57±0.18 : 19 : 5.54 1 : (p.e.) U r s a Major : 1 .50 : 1.54±0.22 : • 5 ! 1 .8 2 a P e r s e i 5.80 : 5.82±0.44 • 7 ! 6.1±0.2 3 O r i o n 0B1 7.93 7.91±0.27 22 7.94±0.48ft Cepheus 0B3 : 9.27 9.48±0.27 : 9 I 9.3±0.5 5 NGC 2244 : 11 .07 : 11.00±0 . 27 : 6 : 10.96±0.44 6 NGC 2264 : 9.29 : 9.17 : 1 : 9.27 7 Cygnus 0B7 : 10.15 : 10.15±0.44 : 6 : 9.35 s 1 C r a w f o r d and P e r r y 1976 2 C r a w f o r d and Barnes 1974a 3 C r a w f o r d and Barnes 1974b " Anthony-Twarog 1982 5 C r a w f o r d and Barnes 1970 6 H e i s e r 1977 7 Becker and F e n k a r t 1971 8 Ruprecht 1966 66 The r e s i d u a l f o r Cyg 0B7 i s + 0 . 8 2 ± 0 . 4 4 m a g n i t u d e s . However, o n l y one d e t e r m i n a t i o n of t h e d i s t a n c e modulus c o u l d be f o u n d ( R u p r e c h t 1966) i n t h e l i t e r a t u r e and t h e u n c e r t a i n t y f r o m t h e H 7 c a l i b r a t i o n i s r a t h e r l a r g e , p a r t l y due t o t h e f a c t t h a t t h e f i t a t t h e h i g h l u m i n o s i t y end o f t h e c a l i b r a t i o n i s n e a r l y v e r t i c a l . F i g u r e s 17 and 18 show a p o s s i b l e d i s c o n t i n u i t y i n t h e v a r i a t i o n o f t h e W(H7) a t an EW of 5-6 A, w h i c h c o r r e s p o n d s t o a dwarf s p e c t r a l t y p e of B2-3 ( s e e t a b l e V I ) . BC r e p o r t f i n d i n g a d i s c o n t i n u i t y a t B4 and b e c a u s e of t h i s f i t two s e p a r a t e l o g c u r v e s t o t h e d a t a , one f o r s p e c t r a l t y p e s e a r l i e r t h a n B4 and t h e o t h e r f o r l a t e r t y p e s . P e t r i e (1965) d o e s n o t m e n t i o n any d i s c o n t i n u i t y i n t h e B2-4 s p e c t r a l r e g i o n . I t may be t h a t t h e s p e c t r a l t y p e c o r r e c t i o n s he employed a c c o u n t e d foi?; i t , however, t h o s e c o r r e c t i o n s i m p l y a d i s c o n t i n u i t y a t B7-8, n o t B2-4. In any e v e n t , an i n s p e c t i o n o f t h e P e t r i e c a l i b r a t i o n does not r e v e a l any o v e r w h e l m i n g e v i d e n c e f o r s u c h a f e a t u r e . o U n f o r t u n a t e l y t h e p r e s e n t d a t a i n t h e 5-6 A r e g i o n o f t h e c a l i b r a t i o n i s i n s u f f i c i e n t t o d e t e r m i n e t h e v a l i d i t y o f a d i s c o n t i n u i t y and, t h e r e f o r e , a smooth c o n t i n u o u s c u r v e has been p u t t h r o u g h t h e d a t a . I t i s e v i d e n t f r o m t h e b i n n e d p o i n t s i n f i g u r e 19, t h a t i f , i n f a c t , t h e d i s c o n t i n u i t y i s r e a l , t h e maximum d e v i a t i o n f r o m t h e p r e s e n t c a l i b r a t i o n w o u l d o n l y be i n t h e ±0.1 mag. r a n g e . T h i s i s a f a c t o r o f 3 l e s s t h a n t h e s c a t t e r a b o u t t h e f i n a l c a l i b r a t i o n (±0.28 mag.). The e f f e c t o f a d i s c o n t i n u i t y , i f r e a l , i s t h u s a m i n o r one. F i g u r e s 20, 21 and 22 show t h e r e s i d u a l s a b o u t t h e mean H 7 -Mv r e l a t i o n . I t would a p p e a r t h a t t h e r e l a t i o n w i l l y i e l d t h e 67 j . j . i .0 0.8 0 0 0.2 0.0 c 2 -0.2 • -0.4 a it -0.6 | - 0 . 8 "3 - J .0 K -J.2 -J .4 3 3 oo _ o co o 0 ° co ° o s; C D - 0 cP £co O ax ——(tO (D rn m ( 5 — O - j H 3 — a o CO OO • do co 0 m © o o CO o CO co 3 t_) 1 .4 J .2 1 .0 0.8 0.6 0 0.2 0.0 £ -0.2 « -0.4 £ -0.6 5 - 0 . 8 •3 - J .0 4J ^ -J.2 -J .4 (#0 xO CO CO co 0® CO ° 0 CO -ax ©x co %> « — © -Of ^ d& co © o o co o x X CO v O x 0 0 X XX o o 2 4 6 8 JO 12 J4 J6 ]8 20 UCHyJ (fl) FIG. 20. Residuals (0-C) about the mean r e l a t i o n f o r c l u s t e r members. JO UO+yj (A) J2 14 J6 J8 20 FIG. 21. Residuals (0-C) about the mean r e l a t i o n . C i r c l e s denote c l u s t e r members, X's zero p o i n t s t a r s . In both f i g u r e s the mean d i s p e r s i o n l e v e l o f ±0.28 mag. i s shown. J .4 -1 .2 • 1 .0 -0 .8 -£ 0 .6 -irve 0 0 .4 -.2 • o c 0 .0 • S u C -0 .2 -• o -0 .4 • u. -0 .6 -—1 0 -0 .8 • Rcslc -J -J .0 -.2 • -1 .4 • 0 3 °5 07 09 Bl B3 B5 B7 B9 Al A3 Spectral Type FIG. 22. The residuals (0-C) in magnitude for stars used in the calibration as a function of spectral type. X's denote n,s,e, and p stars, the crosses supergiants. The mean dispersion level of +0.28 mag. is shown. The A2 supergiant in the bottom right hand corner is the Cyg 0B7 star HD 197345, whose Am= -3.7 mag.. Co 69 b e s t r e s u l t s when n o n - p e c u l a r s t a r s a r e u s e d . In f i g u r e 22 n o t e t h a t out o f 11 n,s, o r e s p e c t r a l c l a s s s t a r s 8 l i e o u t s i d e t h e mean p r o b a b l e d i s p e r s i o n l e v e l o f ±0.28 mag. In a d d i t i o n , t h e r e s i d u a l s o f t h e two p c l a s s s t a r s e x c l u d e d f r o m t h e c a l i b r a t i o n would l i e w e l l o u t s i d e t h i s l e v e l . The A 2 I a s t a r i n Cyg OB7, HD 197345, d e v i a t e s by -3.7 m a g n i t u d e s from t h e mean r e l a t i o n . I t can e a s i l y be seen above t h e mean r e l a t i o n i n f i g u r e s 16 a n d 18. P e t r i e (1965) u s e s d i f f e r e n t s p e c t r a l t y p e c o r r e c t i o n s f o r s u p e r g i a n t s and non-s u p e r g i a n t s l a t e r t h a n B5. W h i l e no s p e c t r a l t y p e c o r r e c t i o n s f o r n o n - s u p e r g i a n t s a r e needed w i t h t h e p r e s e n t c a l i b r a t i o n , i t would a p p e a r some form of c o r r e c t i o n , i n t h e same s e n s e a s P e t r i e ' s , i s needed f o r l a t e B a n d e a r l y A - t y p e s u p e r g i a n t s . U n f o r t u n a t e l y , o n l y 5 s u p e r g i a n t s were o b s e r v e d and, w i t h t h e e x c e p t i o n o f HD 197345, a l l a r e B3 o r e a r l i e r and show no s i g n i f i c a n t s y s t e m a t i c d e v i a t i o n f r o m t h e mean r e l a t i o n . T hus an a n a l y s i s of t h e s u p e r g i a n t d e v i a t i o n i s n o t p o s s i b l e . F o r t h i s r e a s o n t h e c a l i b r a t i o n , i n p r e s e n t form, i s n o t s u i t a b l e f o r s u p e r g i a n t s l a t e r t h a n B3-B4. STELLAR ROTATION EFFECTS The e f f e c t o f s t e l l a r r o t a t i o n on t h e c a l i b r a t i o n was i n v e s t i g a t e d . The r o t a t i o n a l v e l o c i t i e s were f o u n d from t h e FWHM o f t h e XX4200 H e l l , 4387 H e l l , 4471 H e l , and 4481 M g l l l i n e s and a r e d i s c u s s e d l a t e r . A c c o r d i n g t o t h e o r y , t h e e f f e c t of r a p i d s t e l l a r r o t a t i o n i s t o d e c r e a s e t h e s u r f a c e g r a v i t y i n t h e s t a r ' s e q u a t o r i a l r e g i o n due t o c e n t r i f u g a l f o r c e s . As a r e s u l t , t h e h y d r o g e n 70 Balmer l i n e s decrease i n i n t e n s i t y and an e a r l i e r s p e c t r a l type i s mimicked . T h i s e f f e c t has been found o b s e r v a t i o n a l l y . Hartwick and Hesser (1974) f i n d t h a t the H/3 index d e c r e a s e s f o r s t a r s w i t h V s i n i >180 km/sec i n A and F - t y p e s t a r s . Warren (1976) f i n d s a s i m i l a r r e s u l t f o r B s t a r s w i t h V s i n i >250-300 km/sec . Theory a l s o p r e d i c t s ( C o l l i n s 1970) tha t l u m i n o s i t y i n c r e a s e s w i t h r o t a t i o n a l v e l o c i t y . These two e f f e c t s , d e c r e a s i n g hydrogen s t r e n g t h and i n c r e a s i n g l u m i n o s i t y , would seem to a c t a g a i n s t each o t h e r i n a W(H7) or H/3 vs Mv p l o t , and may s i m p l y move a s t a r a l o n g the r e l a t i o n . Hardorp and S t r i t t m a t t e r (1968) have shown i n a t h e o r e t i c a l s tudy t h a t the e f f e c t of r o t a t i o n i n a W(H7)-Mv p l o t i s to i n c r e a s e the s c a t t e r about the mean r e l a t i o n by up to ± 0 . 5 magni tudes . The sense of the d e v i a t i o n s b e i n g dependent on the s t e l l a r i n c l i n a t i o n ang le i . The d e v i a t i o n s are s y m m e t r i c a l about the mean r e l a t i o n , and w i t h a l a r g e sample of s t a r s no s y s t e m a t i c e f f e c t s h o u l d be p r e s e n t . However, from a s tudy of the Sco-Cen a s s o c i a t i o n , G u t i e r r e z - M o r e n o and Moreno (1968) f i n d a dependence of V s i n i on the H/3-Mv c a l i b r a t i o n t h a t s h i f t s the c a l i b r a t i o n to lower l u m i n o s i t i e s f or h i g h e r V s i n i v a l u e s . C o n v e r s e l y , both P e t r i e (1965) and BC f i n d no dependence of V s i n i on t h e i r W(H7)-Mv c a l i b r a t i o n s . F i g u r e 23 g i v e s the d i s p e r s i o n i n a b s o l u t e magnitudes (O-C) about the presen t W(H7)-Mv c a l i b r a t i o n as a f u n c t i o n of p r o j e c t e d r o t a t i o n a l v e l o c i t y . There appears to be a s y s t e m a t i c d e v i a t i o n toward lower l u m i n o s i t i e s f o r V s i n i >230-250 km/sec . T 1.2 -1.0 -V sin 1 Ikm/sccJ FIG. 23. The residuals (O-C) about the mean relation for all stars with determined V sin i values. Note the uneven distribution about the calibration for stars with projected rotational velocities greater than 230-250 km/sec. 72 T h i s " t h r e s h o l d " v a l u e i s s i m i l a r t o t h e v a l u e s f o u n d by H a r t w i c k & H e s s e r and Warren f o r a d e c r e a s e i n t h e H/3 i n d e x . Thus i t would a p p e a r t h a t t h e d e c r e a s e i n t h e h y d r o g e n l i n e i n t e n s i t y i s r e s p o n s i b l e f o r t h e e f f e c t i n t h e W(H7)-Mv r e l a t i o n . F o r t u n a t e l y , not a l a r g e f r a c t i o n of 0 and B - t y p e s t a r s have V s i n i >250 km/sec, and t h u s t h i s e f f e c t s h o u l d n ot be a s e r i o u s c o n s t r a i n t on t h e u s e f u l n e s s o f t h e c a l i b r a t i o n . I t s h o u l d be n o t e d , however, t h a t of t h e 19 P l e i a d e s members u s e d i n t h e c o n s t r u c t i o n of t h e p r e s e n t c a l i b r a t i o n , 7 have V s i n i >250 km/sec. T h i s c l u s t e r , i s p a r t i c u l a r l y i m p o r t a n t a s i t s e r v e s a s t h e a n c h o r s e q u e n c e i n t h e f i t t i n g p r o c e d u r e . The e f f e c t o f so many r a p i d r o t a t o r s i n t h i s c l u s t e r c o u l d be t o i n c r e a s e i t s d e r i v e d d i s t a n c e modulus and t h u s make t h e e n t i r e c a l i b r a t i o n s l i g h t l y b r i g h t e r t h a n i t s h o u l d be. 73 CHAPTER 5 : EVOLUTIONARY EFFECTS E v o l u t i o n a r y e f f e c t s on the s t r e n g t h of the hydrogen Balmer l i n e s have been noted by s e v e r a l i n v e s t i g a t o r s . Crawford (1958) has shown that i n c r e a s e d s t e l l a r age d e c r e a s e s the s t r e n g t h of the Hp a b s o r p t i o n . Bappu, C h a n d r a , Sanwal , and S i n v h a l (1962) f i n d a s i m i l a r e f f e c t on t h e i r p h o t o e l e c t r i c measures of the s t r e n g t h of H 7 and determine the r e l a t i v e ages of d i f f e r e n t e a r l y type c l u s t e r s from a W(H7)- (U-B)o p l o t . Walker and Hodge (1968) f i n d the H 7 a b s o r p t i o n of 05-B2 a s s o c i a t i o n members s t r o n g e r i n a s s o c i a t i o n s c o n t a i n i n g b r i g h t HII r e g i o n s than those w i t h o u t , i m p l y i n g they are l e s s l u m i n o u s . They note i t i s h i g h l y p r o b a b l e t h a t the a s s o c i a t i o n s w i t h the 'br ight HII r e g i o n s are younger than those w i t h o u t . A l l the above r e s u l t s imply t h a t for a g i v e n s p e c t r a l t y p e , the younger a s t a r the g r e a t e r i t s hydrogen a b s o r p t i o n , and thus the l e s s luminous i t i s . F i g u r e s 24a and b show W(H7) vs s p e c t r a l type p l o t s f o r a l l the observed c l u s t e r and a s s o c i a t i o n members. F i g u r e 24a i s by c l u s t e r wh i l e 24b i s by l u m i n o s i t y c l a s s . As the W(H7) i s 04 06 FIG. 24a(above). W(HY) V S spectral type plot for the 8 clusters and associations used to construct the H 7 calibration. The two solid line sequences are as described in the text. The evolved Cyg 0B7 member, HD,197345, is marked. F I G . 24b(below). Same plot as above by luminosity class. 75 c o r r e l a t e d w i t h l u m i n o s i t y t h e s e p l o t s r e p r e s e n t pseudo-HR diagrams. P o i n t s r u n n i n g d i a g o n a l l y a c r o s s each p l o t r e p r e s e n t u n e v o l v e d and s l i g h t l y e v o l v e d main sequence s t a r s . The s u b g i a n t s and g i a n t s t e n d t o l i e s l i g h t l y above t h i s sequence o w h i l e the b r i g h t g i a n t s and s u p e r g i a n t s a l l l i e i n the 1-2 A EW range r e g a r d l e s s of s p e c t r a l t y p e , as e x p e c t e d . Note i n p a r t i c u l a r the Cyg 0B7 A2Ia member HD 197345. The age of the P l e i a d e s i s thought t o be around 150 m i l l i o n y e a r s w h i l e a P e r s e i i s 10 m i l l i o n y e a r s . The r e m a i n i n g c l u s t e r s and a s s o c i a t i o n s , e x c l u d i n g U rsa Major and Cyg OB7, a r e younger. The two s o l i d l i n e d sequences p l o t t e d i n f i g u r e 24a r e p r e s e n t the mean sequences f o r o b j e c t s i n the a P e r s e i a s s o c i a t i o n ( s p . t y . B4-B7) and the P l e i a d e s c l u s t e r ( s p . t y . B7-A2). I t can be seen t h a t the sequence d e f i n e d by the P l e i a d e s ' members l i e s above t h a t of the a Per a s s o c i a t i o n , which i s e x p e c t e d as t h e s e s t a r s a r e more e v o l v e d . A l l t h e observed members from t h e s e two c l u s t e r s have e v o l v e d o f f the main sequence. U n f o r t u n a t e l y , even though the un e v o l v e d main sequence of the a Per a s s o c i a t i o n s t a r t s a t about B8, and would be u s e f u l i n the l u m i n o s i t y c a l i b r a t i o n , no members l a t e r than B7 were o b s e r v e d . P e t r i e (1965) found no e f f e c t on h i s Hy-Mv c a l i b r a t i o n from moderate e v o l u t i o n a r y d i f f e r e n c e s between the v a r i o u s c l u s t e r s used. He s t a t e s t h a t as a s t a r moves o f f the main sequence the s l i g h t e v o l u t i o n a r y changes ( r a d i u s and s u r f a c e t e m perature) " w i l l m e rely move the s t a r a l o n g the H7-M r e l a t i o n " . In o t h e r words, as t h e s t a r ' s l u m i n o s i t y i n c r e a s e s as i t e v o l v e s , the W(H?) d e c r e a s e s by j u s t the r i g h t amount t o move i t a l o n g the 76 r e l a t i o n . However, BC n o t e t h a t t h e r e i s "some e v i d e n c e t h a t t h e b r i g h t e r s t a r s i n t h e a P e r s e i a s s o c i a t i o n and t h e P l e i a d e s ( c l a s s I I I s t a r s ) do t e n d t o be s y s t e m a t i c a l l y b r i g h t e r t h a n P e t r i e ' s c a l i b r a t i o n p r e d i c t s " . A l l t h e s e s t a r s have e v o l v e d o f f t h e main s e q u e n c e . The P l e i a d e s l u m i n o s i t y c l a s s I I I s t a r s l i e a t t h e t o p o f t h e mean s e q u e n c e f o r t h a t c l u s t e r i n f i g u r e s 24a & b, and as s u c h a r e t h e b r i g h t e s t and most e v o l v e d members of t h e c l u s t e r . T h i s c l u s t e r i s e x t r e m e l y i m p o r t a n t t o t h e c a l i b r a t i o n a s i t s e r v e s a s t h e a n c h o r c l u s t e r i n t h e f i t t i n g p r o c e d u r e . The g i a n t s a r e p a r t i c u l a r l y i m p o r t a n t a s t h e s e a r e t h e members p r i m a r i l y u s e d i n f i t t i n g t h e O r i o n OB1 and a P e r s e i ' a s s o c i a t i o n s e q u e n c e s . I f t h e g i a n t s a r e t o o b r i g h t f o r t h e i r e q u i v a l e n t w i d t h s , as s u g g e s t e d by BC, t h e y c o u l d s e r i o u s l y a f f e c t t h e c a l i b r a t i o n . F i g u r e s 25a and b show t h e d e r i v e d d i s t a n c e m o d u l i f o r t h e i n d i v i d u a l c l u s t e r members o f t h e P l e i a d e s and a P e r s e i a s a f u n c t i o n o f a p p a r e n t m a g n i t u d e d e r i v e d f r o m t h e p r e s e n t H 7 c a l i b r a t i o n . I t i s o b v i o u s from b o t h p l o t s , e s p e c i a l l y f o r t h e a Per a s s o c i a t i o n , t h a t t h e b r i g h t e s t , most e v o l v e d members i n e a c h c l u s t e r g i v e s y s t e m a t i c a l l y s m a l l e r c l u s t e r d i s t a n c e s . T h i s i n d i c a t e s t h e y a r e s l i g h t l y b r i g h t e r t h a n t h e c a l i b r a t i o n p r e d i c t s . I t a p p e a r s , t h e n , t h a t s l i g h t e v o l u t i o n a r y e f f e c t s a r e a p p a r e n t i n t h e W(H7)-Mv r e l a t i o n . U n f o r t u n a t e l y , t h e s c a n t y amount o f d a t a f o r b i d s any q u a n t i t a t i v e a n a l y s i s . However, a c l u e t o t h e d e g r e e t h a t s t e l l a r e v o l u t i o n e f f e c t s t h e c a l i b r a t i o n a s a f u n c t i o n o f s p e c t r a l t y p e c a n be d e t e r m i n e d by e x a m i n i n g t h e a Per and Cyg 0B7 a s s o c i a t i o n s . As m e n t i o n e d p r e v i o u s l y , a l l t h e o b s e r v e d members o f t h e a P e r s e i 6.0 > I > 5.0 4.0 7.0 > c i > 4.0 3.0 4.0 5.0 6.0 Vo FIG. 25a(above). Distance moduli derived from the present H 7 calibration vs apparent magnitude, Vo, for Pleiades members. The four giants are shown. FIG. 25b(below). Distance moduli derived from the present H7 calibration vs apparent magnitude, Vo, for aPersei members. The subgiant is shown. 78 a s s o c i a t i o n a r e s l i g h t l y e v o l v e d , and a s s u c h , o n l y e v o l v e d members a r e f i t t e d t o t h e P l e i a d e s s e q u e n c e . I f most o f t h e s e s t a r s a r e t o o b r i g h t f o r t h e i r r e s p e c t i v e EWs one w o u l d e x p e c t t o d e r i v e a s m a l l e r d i s t a n c e modulus t h a n i f u n e v o l v e d s t a r s were u s e d . The d i s t a n c e modulus f o u n d i s i n f a c t 0.3 mag. s m a l l e r t h a n t h e commonly a c c e p t e d one o f 6.1 mag., a l t h o u g h t h e u n c e r t a i n t y o f t h e d i s t a n c e modulus from t h i s s t u d y i s r a t h e r l a r g e ( ± 0 . 4 4 ) . However, t h e o p p o s i t e s i t u a t i o n o c c u r s w i t h Cyg OB7, where some of t h e s t a r s a p p e a r h i g h l y e v o l v e d . The modulus d e r i v e d h e r e i s 0.80 m a g n i t u d e s l a r g e r t h a n t h a t f o u n d by R u p r e c h t . A l s o , t h e e a r l y t y p e Cyg OB7 members ( s p . t y . 05-B3) t h a t a p p e a r e v o l v e d i n f i g u r e s 24a and b do n o t seem t o have any s i g n i f i c a n t s y s t e m a t i c r e s i d u a l s f r o m t h e mean r e l a t i o n . However, t h e A 2 I a s t a r i n Cyg OB7 o b v i o u s l y d o e s . T h i s i n d i c a t e s t h a t e v o l u t i o n a r y e f f e c t s a r e n o t s i g n i f i c a n t f o r t h e e a r l i e s t t y p e s t a r s i n t h e c a l i b r a t i o n . T h i s i s i n agreement w i t h t h e s e n s e o f P e t r i e ' s s p e c ' t r a l t y p e c o r r e c t i o n s f o r s u p e r g i a n t s . The l a t e r t y p e s u p e r g i a n t s (B4 and l a t e r ) need v e r y l a r g e c o r r e c t i o n s a s compared t o t h e e a r l i e r t y p e s . A l s o , C r a w f o r d (1978) o n l y employs e v o l u t i o n a r y c o r r e c t i o n s f o r t h e l a t e r B a n d e a r l y A - t y p e s t a r s i n h i s H 0 c a l i b r a t i o n . The p o i n t s o u t l i n e d above a r e a d m i t t e d l y b a s e d on s c a n t y d a t a and a c l o s e r l o o k a t t h i s a s p e c t o f t h e c a l i b r a t i o n would seem i n o r d e r t o q u a n t i f y t h i n g s . I t would be e x t r e m e l y u s e f u l t o o b t a i n H 7 measures f o r s t a r s o f s i m i l i a r s p e c t r a l t y p e as P l e i a d e s members f r o m a number of c l u s t e r s o f v a r y i n g e v o l u t i o n a r y s t a g e s t o d e t e r m i n e j u s t what, i f any, e f f e c t m o d e r a t e e v o l u t i o n has on t h e l a t e r s p e c t r a l t y p e s i n t h e 7 9 c a l i b r a t i o n . 80 CHAPTER 6 : COMPARISON WITH OTHER CALIBRATIONS F i g u r e s 26-30 show the r e s i d u a l s as a f u n c t i o n of s p e c t r a l type between the p r e s e n t c a l i b r a t i o n and those of P e t r i e (1965), BC, Crawford (1978), Lesh (1978) , and Blaauw (1963) . The mean W(H7) per s p e c t r a l type has been taken from BC, where 1932 OB s t a r s were used to a r r i v e at the means. The f a c t t h a t no ev idence f o r s p e c t r a l type c o r r e c t i o n s i s found f o r l u m i n o s i t y c l a s s e s I I - V may a p p e a r , at f i r s t , to be cause f o r concern s i n c e P e t r i e c o n s i s t a n t l y found the need for them and h i s method of c o n s t r u c t i n g the c a l i b r a t i o n has been c l o s e l y f o l l o w e d . However, a comparison of P e t r i e ' s (1965) f i g u r e 4 and B C ' s f i g u r e 6 show the p l o t s to be s i m i l a r for non-s u p e r g i a n t s . T h i s suggests t h a t i f P e t r i e had not employed h i s s p e c t r a l type c o r r e c t i o n s , the r e s i d u a l s ( P e t r i e - B C ) would have been min imized and c l o s e agreement between the two c a l i b r a t i o n s found f o r a l l s p e c t r a l t y p e s . A l s o , Walker and Hodge (1968) found ev idence t h a t P e t r i e ' s 0 s t a r c a l i b r a t i o n was up to 1.3 magnitudes too f a i n t , a p p r o x i m a t e l y the same amount as the s p e c t r a l type c o r r e c t i o n s for the 06 s t a r s . T h u s , i t may be FIG. 26. The difference between the Petrie (1965) H 7 c a l i b r a t i o n and the present c a l i b r a t i o n . The stars represent Petrie's spectral type corrections for non-supergiants. c • 0 L. to O 1 .0 0.8 I-0.6 0 . 4 0.2 5 -0.0 W u ^ -0.2 i o CD - 0 . 4 r: -0.6 -0.8 •1.0 ©—©—e—a 0 6 0 8 BO — ' J — 1 B2 B4 B6 Spectral Type B8 AO A 2 FIG. 27. The difference between the BC (1974) H 7 calibration and the present calibration. Circles denote luminosity class V, X's luminosity class III. ' CD fV) O . f l r S p e c t r a l Type FIG. 28. The difference between the Crawford (1978) H/3 c a l i b r a t i o n and the present c a l i b r a t i o n . Circles denote luminosity class V, X's luminosity class I I I . CO 0.8 r S p e c t r a l Type FIG. 29. The difference between the Lesh (1979) calibration and the present calibration. Circles denote luminosity class V, X's luminosity class III. CD § 0 . « -a k 0.4 • - J 0 L i 1 i i — 1 1 • 0 6 0 8 BO B2 B4 B6 B8 A O A 2 Spectra! Type FIG. 30. The difference between the Blaauw (1963) c a l i b r a t i o n and the present c a l i b r a t i o n . Circles denote luminosity class V. X's luminosity class I I I . 86 tha t P e t r i e ' s s p e c t r a l type c o r r e c t i o n s are i n e r r o r . The agreement between the present c a l i b r a t i o n and tha t of P e t r i e i s e x c e l l e n t from B0-B7 . The 0 s t a r s are- up to 0.8 mag. b r i g h t e r , and the A s t a r s 0 . 6 - 0 . 7 mag. b r i g h t e r i n the presen t c a l i b r a t i o n . Thus the s u s p i c i o n s of Walker and Hodge and the f i n d i n g s of BC that P e t r i e ' s O s t a r c a l i b r a t i o n i s too f a i n t are c o n f i r m e d . However, the presen t data o n l y p r e d i c t s i t i s too f a i n t by up to 0.8 magnitudes as compared to 1.5 by Walker and Hodge and 1.0 by BC. N o t i c e how the r e s i d u a l s c l o s e l y resemble P e t r i e ' s s p e c t r a l type c o r r e c t i o n s which are a l s o shown in f i g u r e 26. I f i t i s assumed tha t the P e t r i e c a l i b r a t i o n i s too f a i n t for the 0 s t a r s , as appears l i k e l y , the s p e c t r a l type c o r r e c t i o n s are p r i m a r i l y r e s p o n s i b l e as they are of the same magnitude as the r e s i d u a l s from most o ther c a l i b r a t i o n s i n t h i s s p e c t r a l r e g i o n . I t would t h e r e f o r e appear r e a s o n a b l e to assume tha t the s p e c t r a l type c o r r e c t i o n s are main ly r e s p o n s i b l e f o r the r e s i d u a l s observed i n f i g u r e 26 for a l l s p e c t r a l t y p e s , as the r e s i d u a l s and s p e c t r a l type c o r r e c t i o n s agree to w i t h i n the mean s c a t t e r of the p r e s e n t c a l i b r a t i o n , ± 0 . 2 8 mag. T h i s i m p l i e s tha t the P e t r i e s p e c t r a l type c o r r e c t i o n s are indeed i n e r r o r and adds s t r e n g t h to the c o n c l u s i o n t h a t no c o r r e c t i o n s are needed w i t h the p r e s e n t c a l i b r a t i o n . One of the troublesome a s p e c t s of the P e t r i e c a l i b r a t i o n i s that the d e r i v e d d i s t a n c e modulus of NGC 2244 (9.7 ± 0.1 mag.) i s some 1 .2-1 .5 magnitudes lower than o ther d e t e r m i n a t i o n s . T h i s i s a s e r i o u s d i s c r e p a n c y as i t i m p l i e s the c l u s t e r i s at a d i s t a n c e of 870 pc as compared to 1600 pc (assuming a d i s t a n c e 87 modulus of 11.0 m a g . ) . The reason for t h i s d i s c r e p a n c y appears to be due to a c o m b i n a t i o n of P e t r i e ' s H 7 EW v a l u e s f o r NGC 2244 members and the f a c t tha t h i s 0 s t a r c a l i b r a t i o n i s too f a i n t . A comparison of the present measures for the 6 observed c l u s t e r members and P e t r i e ' s v a l u e s f o r the same s t a r s show the presen t H 7 EWs are a l l s m a l l e r (mean M i l l w a r d - P e t r i e r e s i d u a l = + 0 . 9 ± 0 . 5 ( p . e . ) o A ) . In the H 7 - V 0 p lane t h i s has the e f f e c t of s h i f t i n g the present c l u s t e r sequence toward s m a l l e r EWs as compared to P e t r i e ' s sequence. Thus , when the c l u s t e r f i t t i n g t e c h n i q u e i s performed to c o n s t r u c t the p r e s e n t c a l i b r a t i o n , the NGC 2244 sequence has to be s l i d over a g r e a t e r range i n magnitude than the P e t r i e sequence, due to the shape of the c a l i b r a t i o n ( h i g h e r i n t r i n s i c l u m i n o s i t y for s m a l l e r e q u i v a l e n t w i d t h s ) . The d i s t a n c e modulus d e r i v e d here from the f i t t i n g t e c h n i q u e , 11.07 magni tudes , agrees c l o s e l y w i t h o ther d e t e r m i n a t i o n s . U s i n g the p r e s e n t c a l i b r a t i o n and P e t r i e ' s NGC 2244 W (H7) measures , the f i t t i n g t e c h n i q u e g i v e s a d i s t a n c e modulus of 1 0 . 2 ± 0 . 2 magni tudes . The mean s p e c t r a l type of the s i x NGC 2244 c l u s t e r members used i s 0 7 . 5 . The r e s i d u a l ( P e t r i e - P r e s e n t ) between the two c a l i b r a t i o n s a t t h i s s p e c t r a l type i s +0.4 magni tudes . Adding t h i s f a c t o r reduces the d i s t a n c e modulus to 9 . 8 ± 0 . 2 mag. , which agrees w i t h P e t r i e ' s d e r i v e d v a l u e of 9 . 7 ± 0 . 1 mag. T h u s , the c o m b i n a t i o n of P e t r i e ' s W (H7) measures be ing too s m a l l and the h i g h l u m i n o s i t y end of h i s c a l i b r a t i o n be ing too f a i n t account s f o r the h i g h l y anomalous c l u s t e r modulus . T h i s a l s o demonstrates ttie importance of a c c u r a t e W (H7) v a l u e s in d e t e r m i n i n g c l u s t e r d i s t a n c e s . 88 Another troublesome aspec t of the P e t r i e c a l i b r a t i o n , as p o i n t e d out by BC, i s the zero p o i n t c o r r e c t i o n of 5.37 magnitudes , which r e p r e s e n t s the d i s t a n c e modulus of the P l e i a d e s . T h i s compares w i th the Blauuw (1963) v a l u e of 5.55 and the Crawford & P e r r y (1976) v a l u e of 5 .54 . The v a l u e d e r i v e d h e r e , 5 .50 , i s in c l o s e r agreement w i th the above v a l u e s and u n l i k e the zero p o i n t of the BC c a l i b r a t i o n , e s s e n t i a l l y independent of the d i s t a n c e to the Hyades c l u s t e r . The presen t c a l i b r a t i o n averages about 0.1 magnitudes f a i n t e r than the BC r e l a t i o n for a l l main sequence s t a r s and f o r g i a n t s e a r l i e r than B6. For g i a n t s B6 and l a t e r , the BC c a l i b r a t i o n i s about 0.2 magnitudes b r i g h t e r . P a r t of the e x p l a n a t i o n for the observed r e s i d u a l s may l i e i n the z e r o i n g of the c a l i b r a t i o n . BC use Blauuw's (1963) d i s t a n c e to the P l e i a d e s , 5.55 mag . , as t h e i r zero p o i n t . The v a l u e used h e r e , 5 .50 , p r o b a b l y accounts for the e n t i r e c a l i b r a t i o n b e i n g s l i g h t l y f a i n t e r . I t i s i n t e r e s t i n g to note tha t the two c a l i b r a t i o n s agree c l o s e l y , even though BC f i t two s e p a r a t e c u r v e s to t h e i r data wh i l e on ly one was used h e r e . A p p a r e n t l y the d i s c o n t i n u i t y , i f r e a l , does indeed have o n l y a minor e f f e c t on the c a l i b r a t i o n as c o n c l u d e d p r e v i o u s l y . Both the r e v i s e d c a l i b r a t i o n of Crawford and tha t of L e s h are g e n e r a l l y b r i g h t e r than the p r e s e n t c a l i b r a t i o n for the e a r l i e r s p e c t r a l types and f a i n t e r for the l a t e r t y p e s , a l t h o u g h C r a w f o r d ' s i s b r i g h t e r f o r types B 6 - B 9 . A comparison of the H/3 index and W(H7) f o r common s t a r s i s shown i n f i g u r e 31. A l i n e a r l e a s t squares f i t of the form 8 9 H 7 = -104.96 + 41 .67H/3 o i s shown and f i t s t h e d a t a l e s s t h a n 15 A EW v e r y w e l l ( l i n e a r r e g r e s s i o n c o e f f i c i e n t = 0 . 9 7 ) . The t u r n o f f a t t h e u p p e r end i s due t o t h e w i d t h of t h e H/3 f i l t e r . One o f t h e more w i d e l y u s e d c a l i b r a t i o n s i s t h a t o f Blaauw. F o r main s e q u e n c e s t a r s t h e p r e s e n t c a l i b r a t i o n a v e r a g e s 0.4-0.5 m a g n i t u d e s f a i n t e r t h a n Blaauw's f o r t y p e s e a r l i e r t h a n B2, 0.2 m a g n i t u d e s b r i g h t e r f o r B3-B6, and 0.1 m a g n i t u d e s b r i g h t e r f o r t h o s e l a t e r t h a n B7. Blaauw's g i a n t c a l i b r a t i o n , a p p e a r s b r i g h t e r f o r most s p e c t r a l t y p e s , r a n g i n g from 0.7 m a g n i t u d e s a t 09-BO and 0.4 a t B7 t o b e i n g e q u a l a t B2-B3. Note i n p a r t i c u l a r t h e l a r g e r e s i d u a l from 09-B1,2 r a n g i n g up t o 0.8 m a g n i t u d e s a t B0. A l l t h e s e r e s u l t s a r e i n g e n e r a l agreement w i t h BC's f o r l u m i n o s i t y c l a s s e s I I I - V . W a l b o r n (1972) n o t e s t h a t t h e Blaauw c a l i b r a t i o n i s p r o b a b l y t o o b r i g h t f o r 09-B2 main s e q u e n c e s t a r s . The p r e s e n t r e s u l t s a g r e e w i t h t h i s and i n d i c a t e t h a t Blaauw's c a l i b r a t i o n a v e r a g e s 0.4 m a g n i t u d e s t o o b r i g h t e a r l i e r t h a n B2 and up t o 0.8 m a g n i t u d e s a t B0. I t w o u l d a l s o a p p e a r t h i s may be t r u e f o r t h e g i a n t s e a r l i e r t h a n B2. UIH-y) - -104.358 • 4I.661&VJ1 F I G . 31. The r e l a t i o n between the H/3 index and the W(HT) . The best l i n e a r least squares f i t i s shown for data<15 A. The functional form i s above. The point marked (e) represents the s h e l l star 59 Cyg. 91 CHAPTER 7 : ROTATIONAL VELOCITIES The p r o j e c t e d r o t a t i o n a l v e l o c i t i e s , V s i n i , have been de termined u s i n g the ' o l d ' S l e t t e b a k system ( S l e t t e b a k 1954,1956; S l e t t e b a k and Howard 1955) employing the FWHM of the XX4387 H e l l , 4471 H e l , and 4481 M g l l l i n e s . The h a l f widths were taken from the same p r o c e s s e d s p e c t r a from which the H 7 EWs were measured. 35 s t a r s used i n the ' o l d ' S l e t t e b a k system were o b s e r v e d ; of these the XX4387 and 4471 FWHM c o u l d be measured f o r 23 s t a r s and the X4481 FWHM measured f o r a l l 35 s t a r s . These serve as the c a l i b r a t i o n s t a r s . The 'new' S l e t t e b a k system ( S l e t t e b a k et a l . 1975) was not used as on ly 10 s t a r s i n common were o b s e r v e d . I t shou ld be noted tha t the 'new' system produces s m a l l e r r o t a t i o n a l v e l o c i t i e s , e s p e c i a l l y at l a r g e h a l f w i d t h s . F i t s to the c a l i b r a t i o n s t a r s of the form V s i n i = -a + b ( l o g FWHM) f i t the data w e l l and are l i s t e d below for each l i n e X4387 H e l l : V s i n i = -116 .9 + 2 2 3 . 7 ( l o g FWHM) X4471 Hel : V s i n i = -176 .0 + 2 7 4 . 1 ( l o g FWHM) 92 X4481 M g l l : V s i n i = - 27.7 + 1 6 8 . 5 ( l o g FWHM) The f i t s are shown in f i g u r e s 32-34. The one sigma ( l a ) l e v e l i s ± 5 0 km/sec i n a l l three c a s e s . The V s i n i v a l u e s l i s t e d i n t a b l e s I I I and IV are the mean from a l l t h r e e l i n e s u n l e s s o therwise noted (one a s t e r i c = v a l u e from X4481, two a s t e r i c s = mean of X4471 and X4387). F i g u r e s 35 and 36 show compar isons between the r o t a t i o n a l v e l o c i t i e s found here and those from Uese ige and Fukuda (1969) and Ba lona (1975). 93 0 J 2 3 4 S S 7 8 FIG. 54. The V s i n i c a l i b r a t i o n curves for the f u l l width hal f maxima of the X4387 H e l l , X4471 Hel, and X4481 Mgll l i n e s . VjJn J Om/jed nXllvtrd Vain 1 (JO/HCCJ rUiiwa-d FIG. 35(above) § 36(below). Comparison of the present V sin i values with those of Uesugi § Fukuda (1969) and Balona (1975). 95 CHAPTER 8 : SPECTRAL TYPES The c e n t r a l depths of the XX4200 H e l l , 4387 H e l , 4471 H e l , and 4481 M g l l l i n e s were measured from the same p r o c e s s e d s p e c t r a from which the H 7 EWs were t a k e n . The c e n t r a l depths are l i s t e d i n t a b l e s I II and I V . V a r i o u s l i n e r a t i o s were taken to f i n d the most e f f e c t i v e i n p r e d i c t i n g s p e c t r a l t y p e . F i g u r e s 37 and 38 g i v e the best r e s u l t s . The X4200/4471 r a t i o i s an e f f e c t i v e s p e c t r a l type i n d i c a t o r from e a r l y 0 to B0,1 w i t h a s c a t t e r of ± 0 . 5 of a s p e c t r a l t y p e . The X4471/4481 r a t i o i s e f f e c t i v e from B0,1 to A O , 1 . A l t h o u g h t h i s r e l a t i o n c l e a r l y breaks down at types BO and e a r l i e r i t i s extremely t i g h t for types B4 and l a t e r . The mean s c a t t e r i s ± 1 . 0 of a s p e c t r a l t y p e . In both cases e m p i r i c a l f i t s have been made to the d a t a . No attempt has been made to d i f f e r e n t i a t e between d i f f e r e n t l u m i n o s i t y c l a s s e s as not enough non-main sequence o b j e c t s are a v a i l a b l e . From f i g u r e 38, however, i t would appear t h a t s y s t e m a t i c d e v i a t i o n s from the mean f i t may occur f o r l u m i n o s i t y c l a s s e s I-111 at s p e c t r a l types B 0 - B 3 , 4 . Note the t i g h t f i t of 96 a l l l u m i o s i t y c l a s s e s , in the same f i g u r e , f o r s p e c t r a l types B4 and l a t e r . An attempt has been made to see whether there are any s y s t e m a t i c d i f f e r e n c e s i n the s p e c t r a l l i n e r a t i o s between the v a r i o u s c l u s t e r s and a s s o c i a t i o n s . F i g u r e 39 shows tha t no such e f f e c t was found for the X4471/4481 r a t i o . A s i m i l a r n u l l r e s u l t was found for the X4200/4471 r a t i o . Q . UJ O CD d CU C J CD r-9 . 0 8 . 0 7 . 0 6 . 0 5 . 0 4 . 0 3 . 0 2 . 0 1 . 0 0 . 0 - i 1 1 p - -i p 1 1 1 r -CD S ~i 1 1 r-. V + IV o III o II X I 0 4 0 6 0 8 BO B2 B4 B6 B8 AO A 2 Spectral Type FIG. 38. Plot of spectral type vs the r a t i o of the central depths of Hel X4471/MgII X4481 by luminosity class. Q . a 9.0 8.0 7.0 6.0 L° 5.0 c co 4.0 r- 3.0 2.0 1 .0 - i 1 1 1 1 1 r -X - 1 1 1 1 r-0.0 H <!> * x ^ 3 - i 1 1 1 1 1 ' i i . • P l e i a d e s E a P e r s e i + O r i o n O B l <!> C e p O B 3 * C y g OB7 * N G C 2244 X N G C 2264 (D —i 1 1 1 i i 0 4 0 6 0 8 BO B2 B4 B6 B8 AO A 2 S p e c t r a l T y p e FIG. 39. Plot of spectral type vs the ratio of the central depths of Hel X4471/MgII X4481 by cluster and association. 1 0 0 CHAPTER 9 : CONCLUSIONS A new H y - a b s o l u t e magnitude c a l i b r a t i o n for l u m i n o s i t y c l a s s e s I I I - V , c o v e r i n g s p e c t r a l types from e a r l y 0 to A 3 , has been p r e s e n t e d . A s i n g l e r e l a t i o n for main sequence and g i a n t s t a r s has been found and the use of s p e c t r a l type c o r r e c t i o n s i s u n n e c e s s a r y . The presen t c a l i b r a t i o n does not appear s u i t a b l e for l u m i n o s i t y c l a s s e s II and I a , b . The c a l i b r a t i o n averages 0.1 magnitudes f a i n t e r than the BC c a l i b r a t i o n for main sequence s t a r s from 04-A3 and g i a n t s e a r l i e r than B6 . G i a n t s B6 and l a t e r are 0.2 magnitudes f a i n t e r . The p r e s e n t c a l i b r a t i o n i s not n e a r l y as s u s c e p t a b l e to changes in the Hyades d i s t a n c e as i s B C s. B C ' s f i n d i n g that the P e t r i e (1965) 0 s t a r c a l i b r a t i o n i s too f a i n t i s c o n f i r m e d . The p r e s e n t c a l i b r a t i o n i s up to 0.8 magnitudes b r i g h t e r for the 0 s t a r s and up to 0.7 magnitudes b r i g h t e r for the l a t e B and e a r l y A s t a r s . E x c e l l e n t agreement w i th P e t r i e has been found f o r the B0-B7 s t a r s . The H 7 d i s t a n c e modulus of NGC 2244, found i n t h i s s tudy , now appears i n c l o s e agreement w i t h o ther v a l u e s . W a l b o r n ' s (1972) c o n c l u s i o n tha t B laauw's (1963) 101 c a l i b r a t i o n for the 09-B2 s t a r s i s too b r i g h t i s c o n f i r m e d . C o n t r a r y to the f i n d i n g s of P e t r i e and BC, p o s s i b l e r o t a t i o n a l e f f e c t s on the c a l i b r a t i o n are observed for s t a r s w i t h V s i n i g r e a t e r than 230-250 km/sec . There may be s l i g h t e v o l u t i o n a r y e f f e c t s a c t i n g on the c a l i b r a t i o n . I t seems r e a s o n a b l e that e v o l u t i o n a r y e f f e c t s w i l l be more prominent for the l a t e r s p e c t r a l t y p e s . The mean s c a t t e r in a b s o l u t e magnitude about the H 7 r e l a t i o n i s ± 0 . 2 8 mag. T h i s i s a s i g n f i c a n t r e d u c t i o n over the ± 0 . 5 0 mag. s c a t t e r c l a i m e d by BC for t h e i r c a l i b r a t i o n . The p r o b a b l e cause of the reduced s c a t t e r i s the use of h i g h s i g n a l -t o - n o i s e R e t i c o n s p e c t r a which a l l o w s the continuum and l i n e wing placement to be p r e c i s e l y s e t . Use of the s t r e n g t h of the H7 l i n e as a measure of i n t r i n s i c l u m i n o s i t y i n the 0 ,B and e a r l y A - t y p e s t a r s appears p a r t i c u l a r l y u s e f u l f o r g a l a c t i c s t r u c t u r e s t u d i e s . The e a r l y type s t a r s are v e r y luminous and tend to l i e i n g a l a c t i c s p i r a l arms and thus can serve as s p i r a l t r a c e r s out to g r e a t d i s t a n c e s . A grea t advantage of the H 7 method i s that d i s t a n c e s to i n d i v i d u a l f i e l d s t a r s as w e l l as c l u s t e r s may be d e t e r m i n e d . The s m a l l s c a t t e r about the r e l a t i o n ( ± 0 . 3 mag) i s comparable to or b e t t e r than o ther methods p r e s e n t l y employed in d i s t a n c e d e t e r m i n a t i o n s of the 0 and B s t a r s . As the s p i r a l s t r u c t u r e of our ga laxy i s not w e l l de termined o u t s i d e the immediate 2 kpc s u r r o u n d i n g the sun, i t i s these r e g i o n s tha t are of the most i n t e r e s t , and shou ld be i n v e s t i g a t e d . The use of hydrogen l i n e s t r e n g t h s to determine d i s t a n c e s w i l l r e q u i r e s p e c t r a of v e r y f a i n t o b j e c t s . The S tromgren-Crawford uvby H/3 system, and thus 102 C r a w f o r d ' s H/3-Mv c a l i b r a t i o n would not appear s u i t a b l e for these o b j e c t s due to the v e r y narrow i n t e r f e r e n c e f i l t e r s used i n o b t a i n i n g the Hj3 index . Of the two hydrogen l i n e systems, the H 7 method , t h e n , i s more s u i t a b l e f o r f a i n t s t a r s . From the s t a n d p o i n t of the e x t r a g a l a c t i c d i s t a n c e s c a l e , a c a l i b r a t i o n of the W (H7) w i th Mv f o r e a r l y type s u p e r g i a n t s , u s i n g g a l a c t i c s u p e r g i a n t s in c l u s t e r s and a s s o c i a t i o n s to zero the r e l a t i o n , would appear to be a p r o m i s i n g p r o s p e c t as i t i s p o s s i b l e to o b t a i n s p e c t r a of the b r i g h t e s t s u p e r g i a n t s i n g a l a x i e s of the l o c a l group . T h i s s u p e r g i a n t c a l i b r a t i o n may. a l s o have a p p l i c a t i o n s to our own ga laxy i n mapping out the more remote s p i r a l s t r u c t u r e . 103 BIBLIOGRAPHY A b t , H.A. 1978, P u b l . A s t r . S o c . P a c i f i c 90 , 692 An t h o n y - T w a r o g , B . J . 1982, A . J . 87 , 1213 B a l o n a , L.A. 1975, Mem. R. a s t r . S o c . 78 , 51 B a l o n a , L.A., and Crampton, D. 1974, Men. N o t . R. a s t r . S o c . 166 , 203 Bappu, M.K.V., C h a n d r a , S., Sa n w a l , N.B., and S i n v h a l , S.D. 1962, Mon. Not. R. a s t r . S o c . 123 , 521 B a t t e n , A.H. 1967, P u b l . Dom. A s t r o p h y s . Obs. 13 , 119 B e c k e r , W. 1966, Z. A s t r o p h y s . 64 , 77 B e c k e r , W. , and F e n k a r t , R.P. 1971, A s t r o n . A s t r o p h y s . S u p p l . 4 , 241 B e e r , A. 1961, Mon. Not. R. a s t r . S o c . 123 , 191 B l a n c h a r d , P., Bowen, W.E., L e d d e n , J . E . , P e a r s o n , E.A., P i e g o r c h , W.U., Tymon, P.A., U r c i u o l o , L.R., Ward, R., an Z a w a c k i , D. 1974, A . J . 79 , 809 Blaauw, A. 1963, i n B a s i c A s t r o n o m i c a l D a t a , V o l I I I of S t a r s and S t e l l a r S t s t e m s , e d . K.A. S t r a n d ( U n i v e r s i t y o f C h i c a g o , C h i c a g o ) , p.383 Blaauw, A., H i l t n e r , W.A., and J o h n s o n , H.L. 1959, A p . J . 130 , 69; i b i d . JJLL > 5 2 7 ( e r r a t u m ) C o l l i n s , G.W., I I . 1970, i n S t e l l a r R o t a t i o n , e d . A. S l e t t e b a k ( R e i d e l , D o r d r e c h t ) , p.85 Crampton, D., L e i r , A., and Y o u n g e r , F. 1974, P u b l . Dom. A s t r o p h y s . Obs. j_4 , 151 C r a w f o r d , D.L. 1958, A p . J . 128 , 185 1978, A . J . 83 48 C r a w f o r d , D.L and B a r n e s , J.V. 1969, A . J . 74 407 1970, A . J . 75 952 1974, A . J . 79 687 C r a w f o r d , D . L . , and P e r r y , C . L . 1976, A . J . 8J_ , 419 D i d e l o n , P . 1982, A s t r o n . A s t r o p h y s . S u p p l . 50 , 199 Eggen, O . J . 1963, A . J . 68 , 483 1965, O b s e r v a t o r y 85 , 104 F i t z G e r a l d , M . P . 1969, P u l b . A s t r o n . Soc . P a c i f i c 8J_ , 71 G a r r i s o n , R . F . 1970, A . J . 75 , 1001 G u n t h e r , S. 1933, Z . A s t r o p h y s . 7 , 106 G u t i e r r e z - M o r e n o , A . , and Moreno, H . 1968, P u b l . Dept . A s t r o n . U n i v . C h i l e 1 , 72 Hanson, R . B . 1980, S t a r C l u s t e r s , IAU Symp. No.85, e d . J . E . Hesser ( R e i d e l , D o r d r e c h t ) , p.71 H a r d o r p , J . , and S t r i t t m a t t e r , P . 1968, A p . J . 153 , 465 H a r t w i c k , F . D . A . , and H e s s e r , J . A . 1974, A p . J . 192 , 391 H e a r d , J . F . , and F e r n i e , J . D . 1967, D e t e r m i n a t i o n of R a d i a l V e l o c i t i e s and T h e i r A p p l i c a t i o n , IAU Symp. No.30, e d . A . H . Bat ten and J . F . H e a r d , (Academic , L o n d o n ) , p.219 H e i s e r , A . M . 1977, A . J . 82 , 973 Humphreys, R . M . 1978, A p . J . S u p p l . 38 , 309 Johnson , H . L . 1962, A p . J . 136 , 1135 1965, A p . J . J_4J_ , 923 Johnson , H . L . , and I r i a r t e , B . 1958, Low. Obs . B u i . 4 ,47 Keenan, P . C . 1963, i n B a s i c A s t r o n o m i c a l Data , V o l I II of S t a r s ans S t e l l a r s Systems, e d . K . A . S t r a n d ( U n i v e r s i t y of C h i c a g o , C h i c a g o ) , p.78 L a c y , C . H . 1979, A p . J . 228 , 817 L e s h , J . R . 1979, i n S p e c t r a l C l a s s i f i c a t i o n of the F u t u r e , e d . M . F . M c C a r t h y , S . J . , A . G . D . P h i l i p , and G . V . Coyne, S . J . ( C i t t a d e l V a t i c a n o , S p e c a l a V a t i c a n a ) , p.81 Mendoza, E . E . , V . , and Gomez, T . 1980, Mon. Not . R. a s t r . Soc . 190 , 623 Murphy, R . E . 1969, A . J . 74 , 1082 P e a r c e , J . A . , and H i l l , G . 1975, P u b l . Dom. A s t r o p h y s . Obs . J_4 , 319 105 P e t r i e , R . M . 1950, P u b l . Dom. A s t r o p h y s . Obs . 8 , 319 1953, P u b l . Dom. A s t r o p h y s . Obs . 9 , 251 1965, P u b l . Dom. A s t r o p h y s . Obs . J_2 , 317 P e t r i e , R . M . , and H e a r d , J . F . 1970, P u b l . Dom. A s t r o p h y s . Obs . J_3 , 329 P e t r i e , R . M . , and L e e , E . K . 1966, P u b l . Dom. A s t r o p h y s . O b s . 13 , 435 P e t r i e , R . M . , and M a u n s e l l , C D . 1950, P u b l . Dom. A s t r o p h y s . Obs . 8 , 253 P e t r i e , R . M . , and M o y l s , B . N . 1956, P u b l . Dom. A s t r o p h y s . Obs . • 10 , 287 Popper , D . M . 1980, Ann . Rev. A s t r o n . A s t r o p h y s . 18 , 115 P r i t c h e t , C . J . , M o c h a n a c k i , S . f and Yang, S. 1982, P u b l . A s t r o n . Soc . P a c i f i c 94 , 733 R u p r e c h t , J . 1966, T r a n s . IAU 12B , 350 S l e t t e b a k , A . 1954, A p . J . U9 , 146 1956, A p . J . V24 , 173 S l e t t e b a k , A . , C o l l i n s , G . W . , I I . , Boyce , P . B . , W h i t e , N . M . , and P a r k i n s o n , T . D . 1975, A p . J . Suppl. 29 , 137 S l e t t e b a k , A . , and Howard, R . F . 1955, A p . J . J_21_ , 102 S t o c k , J . 1956, A p . J . J_23_ , 253 U e s u g i , A . , and Fukuda, I . 1969, C o n t r i b . I n s t . A s t r o p h y s . Kwasan O b s . 189 , 205 Walborn , N . R . 1972, A . J . 7_7 , 312 W a l k e r , G . A . H . 1 977, J o u r n a l R. a s t r . S o c . C a n . 7J_ , 139 W a l k e r , G . A . H . , and Hodge, S . M . 1966, P u b l . Dom. A s t r o p h y s . Obs . J_2 , 401 1968, P u b l . A s t r o n . Soc . P a c i f i c 80 , 474 Warren , W . H . 1976, Mon. N o t . R. a s t r . Soc . 174 , 111 Warren, W . H . , and H e s s e r , J . E . 1978, A p . J . S u p p l . 36 , 497 Weaver, H . F . , and E b e r t , A . 1964, P u b l . A s t r o n . Soc . P a c i f i c 76 , 6 106 APPENDIX A A t o t a l of 18 new s p e c t r o s c o p i c b i n a r y c a n d i d a t e s , p l u s 8 more p o s s i b l e SBs, have been found from i n s p e c t i n g the r e c t i f i e d R e t i c o n s p e c t r a for l i n e b l ends due to secondary components. These s t a r s are noted i n column 14 of t a b l e I I I . F i g u r e s A-1 through A-6 are t y p i c a l examples of these s p e c t r a i n the r e g i o n X4300 to X4500. I NTENS ITY HD 238S0 : Pleiades aeaber : Sp. Ty. B8III : S/N - 700 : Data Smoothed HD 35149 : Orion OBI meunbtx : Sp. Ty. B2.5V : S / N = 240 : Data Smoothed 1 .02 0 .64 L 1 1 1 4294.6 4345.5 4396.4 4447.3 WAVELENGTH (flj F I G . A-3 HD 22328 : Alpha Per member : Sp. Ty. BSIVn : S/N - 550 : Data Smoothed HD 216066 : Ccp 0B3 member s Sp.Ty. B1.SV S/N - 120 : Data Smoothed 1.02 i . UflVELENGTH (flj F IG . A-5 HD 216532 : Ctp 0B3 member : Sp. Ty. 08V : S/N - 110 : Data Smoothed F IG . A-6 

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