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UBC Theses and Dissertations

Carbon stars in the large magellanic cloud Crabtree, Dennis Richard 1976

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CARBON STARS IN THE LARGE MAGELLANIC CLJUD  by  Dennis Richard Crabtree  B.Sc.  U n i v e r s i t y o f B r i t i s h Columbia, 1974  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS  FOR THE DEGREE OF  MASTER OF SCIENCE  i n the Department of GEOPHYSICS and ASTRONOMY  We accept t h i s  t h e s i s as conforming t o the  required  The U n i v e r s i t y  standard.  of B r i t i s h  Columbia  August, 1976 ©  Dennis R i c h a r d C r a b t r e e 1976  In p r e s e n t i n g t h i s t h e s i s  in p a r t i a l f u l f i l m e n t o f the requirements f o r  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n  f o r e x t e n s i v e copying o f t h i s  thesis  f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department by h i s  representatives.  It  i s understood that copying or p u b l i c a t i o n  o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d without my written  permission.  Depa rtment The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1WS  or  ii  Abstract  A catalogue Cloud  is  of c o o l carbon s t a r s i n  presented  along  with  photometric  o b s e r v a t i o n s of some of the members. dispersion order to spectrum.  of  117 A/mm  investigate In  addition  of  the  photometric  Large and  Image tube  were obtained some  the  Magellanic  spectroscopic spectra  at  a  f o r seven of the s t a r s i n grosser  features  observations  on  of  the  the  VEI  system of f o r t y s t a r s have been made.  The observed isotope.  spectra  indicate  that  three  the  carbon  Using the photometric  and,  the formation  (2)  the helium  l 3  C  o b s e r v a t i o n s to place the s t a r s diagram,  it  is  (1) a l l f o r t y s t a r s are i n the d o u b l e - s h e l l sourca  evolution  stars  show enhancement of s p e c t r a l f e a t u r e s i n v o l v i n g the  in a t h e o r e t i c a l Hertzsprung-Hussell that  of  concluded phase of  s h e l l f l a s h e s are r e s p o n s i b l e f o r  of the m a j o r i t y of c o o l N-type carbon  v  stars.  iii  Table  of  Contents page  I  II Catalogue of III IV  1  Introduction Carbon S t a r s  Photometric Observations  66  Spectroscopic  76  Observations  V Carbon S t a r s i n the VI  5  Summary Bibliography  H-B  Diagram  87 98 101  iv  List  of  Tables page  I. II. III. IV. V. VI.  Plate Centres  8  Carbon S t a r  Coordinates  9  Carbon  Photometry  67  Star  Spectroscopic Properties  Observations  o f t h e Seven C a r b o n S t a r s  Classification  o f Carbon  Stars  79 81 82  List  of Figures page  1.  Finding Charts  27  2.  V versus  R-I  70  3.  V versus  V-I  71  4.  V versus  V-E  72  5.  Mbol  versus  V-R  74  6a.  Carbon S t a r S p e c t r a , r e g i o n  1  77  6b.  Carbon S t a r S p e c t r a , r e g i o n 2  78  7.  Bolometric Corrections  88  8.  Colour  9.  Theoretical  Temperature  versus  R-I  H e r t z s p r u n g - R u s s e l l Diagram  92 93  vi  Acknowledgements  I would l i k e to thank my s u p e r v i s o r Harvey patience work.  and  enthusiastic  support  during  I thank B.I. Olson f o r s u p p l y i n g  programs  used  i n t h i s study.  many  fixcher  for  the course of t h i s of  the  computer  I a l s o thank B.E. Westerlund f o r  k i n d l y supplying the o r i g i n a l c h a r t s on which he had marked suspected  program  stars.  I  thank  the  the U n i v e r s i t y of B r i t i s h  Columbia f o r support from a postgraduate f e l l o w s h i p . would  his  Finally  I  l i k e t o thank the graduate students of the department f o r  making the department such an enjoyable place to work.  1  I  Introduction  Among t h e s t a r s groups of  classified  as r e d  which show a n o m a l o u s a b u n d a n c e s  these  groups  is  the  enhancement o f a b s o r p t i o n  carbon  giants  of c e r t a i n  stars.  the  classified members. was  Henry  Shane (1928)  sequence  as  Subsequently  abundance.  that  was  solved  system  that  stars.  and  abundances  each s t a r  deficiency  of  the  cn C  the  system  One  show  for  Henry  the  redder but i t  temperature  Draper  system.  proposed  the  on t e m p e r a t u r e a n d  classification  must be a b l e  in  originally  subdivsions  problem.  has  C-  carbon by  no  Any  classification  to  sort  out  the  as t h e t e m p e r a t u r e s e q u e n c e  has d e v i s e d  C  a system  classification  is  that  in  i n which  he  as w e l l  as  system.  the sequence  not r e p r e s e n t a t r u e temperature  an  isotope.  of e l e v e n s p e c t r a l f e a t u r e s  from  sequence  One C5-C9  ( Richer  1973) .  Much o f t h e t h e o r e t i c a l hampered  of  as w e l l  Xamashita(1967)  the  C  not a t r u e  Morgan (1941)•  classification  classifying  does  of  system  estimates the i n t e n s i t i e s  1971 ; S c a l o  rest  f o r c a r b o n s t a r s based  the  3  these into was  many  including,  reserved  system  i s t o be s u c c e s s f u l  many d i f f e r i n g  probably  being  this  the  However t h i s  means  these  later  N  reclassified  Keenan  classification  1  stars  D r a p e r C a t a l o g u e t h e s e s t a r s were  as t y p e R o r N;  discovered  the  are  elements.  These  bands o f CH,CN, and  some c a s e s , bands o f m o l e c u l e s i n v o l v i n g  In  there  by  the  lack  of  work good  on  carbon  absolute  stars  has  v i s u a l magnitudes  been for  2  individual objects. 1972,1975;Olson involved and  i s not  and  fact  to  o b j e c t s are  measure  o b j e c t s run  i n t o the  endeavor;  no  trigonometric clusters, effect for  are  two  The  of  an  temperatures Johnson (1965) ;  our of  Galaxy,  individual  enough  reliable  to  are  have  a  rarely  systens,  R s t a r s and  this  members  the  of  iilson-Bappu  impossible  to  use  radius  classes do  that  not have  the  binary of  nor  the  and  has  been  stars  well  obtained or  M g i a n t s {Bahng 1966;Scalo 1973). and  A  direct  parallax.  in  with by  Wing (1967)  Colour-colour  a c a l i b r a t i o n between c o l o u r  X Cue.  a measurable  later  c o o l carbon s t a r s r a d i a t e  i s based on normal M g i a n t s  the  s i n c e no carbon s t a r i s a  correlate  Richer (1971)  to  r a d i i or carbon s t a r s .  19 Psc  is difficult  eclipsing  related  t h e i r angular diameters measured  occultation,  photometric o b s e r v a t i o n s .  use  rare i n  from  in  binary  method of l u n a r  classification  do  subtypes  problems encountered  members o f  f o r the  stars  Tins follows  magnitudes  stars  t o use  of  spectral  objects.  carbon  carbon s t a r s have had  temperature  that  a l l the  e f f e c t i v e temperature and  measurement of the member  close  1968;Eicher  number  absolute magnitude problem i s c l o s e l y  problems of the  by the  is  the  relatively  s o r t of  Gordon  N stars,etc.  The  Only  but  absolute  usual  parallax,  is difficult  the  the  object  few  1975)  observed i n these  that these  attempts  Richer  exist(  l a r g e enough t o c o v e r  peculiarities  the  Seme r e s u l t s do  the  the  colour  Mendoza from  relations  C  and  extensive  have  shown  more l i k e b l a c k - b o d i e s than Therefore  any  attempt  e f f e c t i v e temperature  should be t r e a t e d  with  caution.  to that  3  Hallerstein(1973) properties  a  good  review  of  the  physical  of carbon s t a r s as w e l l as one p o s s i b l e e v o l u t i o n a r y  seguence. stars  gives  The carbon s t a r s are  that  are  exhibiting  believed  to  the products  be  well  evolved  of n u c l e o s y n t h e s i s i n  t h e i r outer atmosphere.  The carbon  first stars  part of  this  in  Large  these s t a r s should large  dispersion  accurate  be p o s s i b l e to  on  presented  together with image  brighter  members.  effective  relation  temperature,  Hertzsprung-Russell  indicate  tube  catalogue  southern  magnitudes  better  locate  spectra  of  i s presented itself  is  C  these  between  s t a r s are  seven  of the  for bolometric  photometric  colour  The  results  are  compared  and  isotope. in  members molecular  A d e t a i l e d d i s c u s s i o n of the  section  presented  with  stars.  three o f the seven show enhancement of l 3  and  Along with the c a t a l o g u e ,  medium d i s p e r s i o n s p e c t r a of the s e v e n • b r i g h t e r that  several  these s t a r s a r e placed i n a t h e o r e t i c a l  diagram.  bands c o n t a i n i n g the spectra  the  the VBI system of f o r t y  c u r r e n t models o f the c o o l carbon  The  in  Using the best a v a i l a b l e data  corrections'and'the  that  carbon s t a r s i n the Large  s t a r s i n c u r r e n t e v o l u t i o n a r y models. observations  of  A catalogue of  absolute  of  calalogue  now  operational  spectra  M a g e l l a n i c Cloud i t should  photometric  a  Magellanic Cloud.  becoming  I f one o b t a i n s  medium  contains  be a very u s e f u l ' document  t e l e s c o p e s - are  hemisphere. good  the  thesis  in  IV  of  this  thesis.  The  II  while  the  section  4  photometric  o b s e r v a t i o n s are d i s c u s s e d i n s e c t i o n I I I .  Section  V c o n t a i n s a d i s c u s s i o n of the Hertzsprung-Russell diagram respect of the  with  t o the carbon s t a r s while s e c t i o n VI c o n t a i n s a summary results.  5  I I Catalogue of Carbon  The number  Stars  most e f f i c i e n t of  objects  is  method i s p a r t i c u l a r l y spectra  are  spectra.  easily  The  to d i s c o v e r  to use  and  an o b j e c t i v e prism  separable  from  stars  most  i n c l u d e emission  discussed  who  Magellanic  Cloud  plates  has  below  kindly  marking  were  obtained  charts  oi  on  the  with the  Mavridis stars  1967).  were  Other CN  plate  the  A/mm  I-N  the  The CN  Large  main  most  criteria  indicators  bands at  bands shortward of  the  objective  bands,  T h i s a l s o reduces the other  magnitude and  the  Dr.  at  Carbon s t a r s are  stars  i n t h i s r e g i o n of the spectrum.  using  B.E.  20/26 i n c h Schmidt t e l e s c o p e  since  reached t o about 1=14  identified  Dr.  suspected carbon s t a r s on them.  1  f a i n t e r (absolutely)  were  planetary  i d e n t i f i e d by  supplied  reason f o r u s i n g I - N p l a t e s .  obtained  whose  astronomical  much b r i g h t e r i n the I band than e i t h e r the B or V  of"spectra  This  objects  stars,  Uppsala Southern S t a t i o n on Mount Stromlo.  the  large  survey.  other  line  westerlund i d e n t i f i e d these s t a r s from 2100  the  for  a  carbon s t a r s .  Hesterlund  prism  classify  u s e f u l i n the search  Such o b j e c t s  nebulae and  way  the  thus  overlap  are  much  The  plates  carbon  stars  e s t a b l i s h e d by .Nassau ( c f . used  ^7945 A,  to  ^8125  atmospheric  identify A and  these  ^8320 A.  A-band { )\7600  A)  appear only when the spectrum i s h e a v i l y overexposed.  Hesterlund(1964) has plate  given  a preliminary  d i s c u s s i o n of  m a t e r i a l emphasizing the d i s t r i b u t i o n of the carbon  this stars  6  w i t h i n the Large stars  tend  M a g e l l a n i c Cloud.  He  that  structural  features  He a l s o noted  clusterings  noted  exposed photographs*  that  they  by  agreed  well  de Vaucouleurs(1955) a l s o estimated  the  on h e a v i l y mean  The c h a r t m a t e r i a l c o n s i s t e d of two separate s e c t i o n s .  The  first  Westerlund  with  the  apparent  that  v i s u a l magnitude was 15.7± 0.5.  section  was  at  a s c a l e o f about  11.8" arc/mm while the  second s e c t i o n , which a l s o i n c l u d e d a l l the f i r s t a  1974  carbon  t c form c l u s t e r i n g s , p o s s i b l y i n the shape of arms , and  that the p o s i t i o n of these  at  the  t o a v o i d the c e n t r a l r e g i o n s as well as t h e r e g i o n s  r i c h i n n e b u l o s i t y and i n blue s t a r s . appear  found  scale  of  27" arc/mm.  while the second  method  s e t was  section,  was  The f i r s t s e t was measured i n May measured  in  August  1975.  The  used t o get frcm the X,Y p o s i t i o n t o r i g h t a s c e n s i o n and  declination Briefly,  on  the  i t consists  sky  is  of  that  described  considering  by  Smart (1971).  the tangent plane and a  s t a r ' s p r o j e c t e d p o s i t i o n on t h i s plane i f the t e l e s c o p e i s not p o i n t e d d i r e c t l y a t t h i s s t a r (as i n a photograph). which at ue  The point at  t h e tangent^plane c o n t a c t s the c e l e s t i a l sphere(the p o i n t  which the t e l e s c o p e i s aimed) i s taken to be the o r i g i n .  If  take the meridian of t h i s p o i n t , i t p r o j e c t s i n t o a s t r a i g h t  l i n e on the tangent orthogonal  plane.  coordinate  This l i n e  system  on  forms  the  sky.  one  coordinates  of  the  image  of  f o r an  The other a x i s i s  taken t o be a l i n e drawn p e r p e n d i c u l a r to the f i r s t standard  axis  the  axis. star  on  photographic p l a t e a r e found with r e f e r e n c e to r e c t a n g u l a r drawn  The the axes  through the c e n t r e of the p l a t e and drawn p a r a l l e l to the  7  orthogonal axes on the sky. stars,  the  By using three  standard  reference  p l a t e constants r e l a t i n g the measured X-Y  positions  t o the standard c o o r d i n a t e system can be c a l c u l a t e d . plate  constants  from  X-Y  Once  the  have been e v a l u a t e d i t i s an easy matter to go  values  to  standard  coordinates  co  eguatorial  coordinates.  The  first  set  of  charts  were  measured  d r a f t i n g t a b l e using a d r a f t i n g sguare To  check  the  accuracy  of  the  on  a  and a m i l l i m e t e r r u l e r  measurements  each  measured twice and the r e s u l t i n g c o o r d i n a t e s averaged The  second  set of c h a r t s were measured on the X-Y  the Department of Mechanical check  the  standard  E n g i n e e r i n g at UBC.  together.  of  the  suspected carbon  p o s i t i o n s of  s t a r s were measured.  the t r a n s f o r m a t i o n to r i g h t ascension completed  the  and d e c l i n a t i o n  charts  accuracy at the  was  the  coordinates  confirmed,  telescope.  centres  of  each  measured and the  had  the After been  computed c o o r d i n a t e s of the r e f e r e n c e s t a r s were  compared to those t a b u l a t e d i n the SAO of  of  order .to  three b r i g h t r e f e r e n c e s t a r s were measured at the same time positions  was  digitizer In  a c c u r a c y of the t r a n s f o r m a t i o n s the X-Y  chart  good  In both  sets  to about 10" a r c .  This  as a l l the s t a r s were found q u i t e e a s i l y  Table of  are  catalogue.  I  contains  the  approximate  the f i e l d s as w e l l as the number of  number  of  stars  for  which  photometry  plate stars was  obtained.  Table  II  contains a l i s t  of the coordinates f o r the epoch  1975.0 of a l l the suspected carbon  stars.  Finding  charts  for  Table I P l a t e r~?ield  1 I  !  1 1 1 1 i  I  1 1 1 1  i  1 1  R. A.  1.  I  * 50  2.  I  *» 4 5  3.  J  4 40  4.  !  5 20  5.  I  5 20  6.  I  5 20  7.  I  5 50  8.  I  5 55  9.  |  6 00  20.  i  6 05  23.  I  6 30  24.  !  6 40  J  1 i•  I  1 1 1 i  i  I  -i  .„..., .  Centres  # of Carbon 1 s t a r s found j j. j 29  I I  Dec.  I i I  -60O  -69°  14  I  -720  18  I  -660  33  1 1  -690  24  i  -720  76  I  -660  3  -690  14  -720  36  -750  4•  -690  51  -720  3  I  \  ji  1 1 1 1 i t 1 1 1 i i  1 1  is  approximately  top and east t o the  13  20  I  i...  these s t a r s are presented i n F i g . 1. charts  # of S t a r s Paotometry  left.  11  * a r c by  The 16»  f i e l d of these  finding  arc with n o r t h t o the  T a b l e I I Carbon s t a r  L.M.C. F i e l d Star  9  coordinates  #1  Right  Ascension  (1975)  Declination  1  4  h  52™ 2 8  2  4  h  53™ 2  3  4  h  58  4  5  h  0  m  12  s  -66°28l2  5  5  h  l  m  19  S  -66°52!9  6  5  h  2  m  7  5  h  2  m  8  5  9  4  h  5 9™ 0 0  S  -65°57!7  10  5  h  l  41  S  -65°5l!9  11  5  h  2  m  53  S  -65°58!9  12-  5  h  3  m  11  S  -66°2!9  13  5  h  2  m  47  S  -66°26!5  m  9 17  2  h  -66°28!o  S  -66°27 ! 0  s  36  -66°52!4  s  •  S  m  -67°12l5  s  3  -67°18!l -66°57!o  s  28  m  ,  14  5  15  5  h  4  m  50  S  16  £  h  5  m  50  S  17  4  h  58  m  43  S  -65°26l6  18  4  h  58  m  32  S  -65°22l2  .h  25  -66°55.9 -67°13!l -66°15'.3  s  '  4  20  5  h  0  m  26  S  - 6 5 ° 2.'5  21  5  h  2  m  22  S  -65° 9 ^  22  5  h  2  m  43  S  -65°ll!l  23 24  4 4  h  53 50  S  -64°37!9 - 6 7 ° o!7  m  m  13  '  19  h  59  m  23 32  (1975)  s  -64°59.0  10 Table I I cont'd  L.M.C. Star  Field  //1 Right  Ascension  (1975)  Declination  (1975)  25  4  h  49  m  28  s  -67°16!3  26  4  h  50  m  34  s  -67 10.'6  27  4  h  52  m  30  s  -67°11 ! 1  .28  4  h  57  m  56  s  29  5*  1  0  m  3  s  o  -67°19!4 -67°14.'5  11 Table  L.M.C.  Field  Star  I I cont'd  #2 Right  (1975)  Ascension  Declination  1  4  h  33  m  51  S  -70°15!6  2  4  h  39  m  5  S  -7o°io!o  3  4  h  40  m  12  S  4  4  h  49  m  48  s  -69°58l8  5  4  h  52  m  54  s  -69°57 !4  6  4  h  53  m  44  s  7  4  h  55  m  25  S  8  4  h  54  m  39  S  9  4  h  55  m  11  10  4  h  55  m  43  s  -7 0°  11  4  h  55  m  35  S  - 7 0 ° 9l7  12  4  h  58  m  39  S  -70°ll!3  13  4  h  59* 1 9  S  14  5  h  0  m  (1975)  -7 0 ° 1 3 ! 1  -67°4l!4 -68°54!2 -7 0° 2'.3 -7 0° 2!8  S  23  S  l'.9  -70°lo!3 -7 0°15!7  Table I I cont'd  L.M.C. Star  Field  //3 Right  Ascension S  -70°52!5  34  S  -70°39'4  4 4* 5 6  s  -70°31!3  43  s  -72°28.'o  9  S  -72°45.'l  0  s  -73°18l5  15  s  -71°  35  s  -70°25!6  24  s  -70°38l3  4  h  41  m  2  4  h  42  m  3  4  h  .  4  h  48  5  4  h  5 l  6  4  h  53  7  4  h  8  4  h  9  4  h  10  4  h  11  4  h  12  4  13  m  m  m  m  50 50 53  m  m  53  m  57  m  h  55  m  4  h  56  14  4  h  15  4  h  16  4  h  17 18  "  5  m  m  58  5  57  m  58 h  h  Declination  46  1  4  (1975)  I  m  -71°15!2  s  2  s  -73°14\5  28  s  -70°21 '.9  14  S  -70°2o!o  3  S  -70 5o!4  50  S  - 7 1 ° 2 1 !8  41  S  -71°58!5  s  m  o  I  52 m  3!o  36  S  D  -7 2° 56'.6 - 7 1 ° 14*. 5  (1975)  Table I I cont'd  L.M.C. F i e l d Star  if h Right  Ascension  1  5  h  2  5  h  3  5  h  4  5  h  5  5  h  6  5  h  7  5  8  7  m  .8  8  m  .4 4  (1975)  Declination -64°27!.2  S  -64°42.3  s  l l  m  31  S  -64 11.'9  12  m  31  s  -64°14!l  ll  m  50  s  -65°  l l  m  42  s  -65°16!1  h  15  m  17  s  5  h  16  m  9  S  9  5  h  17  m  10  s  10  5  h  19  m  45  S  11  5  h  2  S  -64°54.7  12  5  h  4  m  55  S  -64°30'.7  13  5  h  9  m  21  s  14  5  h  16  m  34  S  -64°2l!l  15  5  h  8  m  54  S  -65°43. 7  io  m  44  S  -65°42'. 1  16  .  5  23  h  m  0  -65°  9!8  9.6  -64°52!l -64°48!5 -65°  4.'2  -64°28:2  !  17  5  h  12  m  6  S  -65°47'.6  18  5  h  12  m  55  S  -65°43l3  19  5  h  15  m  33  S  20  5  h  5  m  59  S  21  5  h  7  m  46  S  -66°  22  5  h  3  m  32  S  -66°23l2  23  5  h  6  m  13  S  -66°26!4  24 '  5  h  8  m  24  S  -65  o  '  47.5  -65°58.8 5.5  -66°26!8  Table I I cont'd  L.M.C.  Star  Field  #4  Right  Ascension ll  25  5  h  26  5  h  27  5  h  10  28  5  h  29  (1975)  Declination  44  s  44  s  - 6 7 °  m  50  S  -67°27  15  m  19  s  5"  16  m  28  30  5  h  19  m  3 9  s  - 6 7  0  3 6 ! 6  31  5  h  20  m  4 4  s  -67  0  37!4  32  5  h  15  m  33  5  h  14  m  m  6  m  4 15  -66°52l7 4*.9 '.2  -67°15:9  -64°48!4  s  s  - 6 5 °  3 ^  (1975)  Table I I cont'd L.M.C. F i e l d Star  #5 Right  Ascension  1  4  h  2  5  h  3  5  h  4  5  h  5  5  h  6  5  h  7  5  h  8  5  h  8  9  5  h  4  m  10  5  h  7  m  11  5  h  9  m  12  5  h  9  m  13  5  h  14  5  h  15  5  h  16  5  h  17  *  5  h  18  5  h  19  5  h  20  5  h  21  5  h  22  5  h  23  5  h  24  5  h  59  m  o  m  2  m  2  m  3  m  3  m  3  m  io  S  -67°l4!l  47  S  - 6 9 ° 9*0  s  -68°55!6  S  -68°46!l  38  s  -68°35!5  35  S  -68°19l7  43  s  -67°39\l  54  s  -67°26!2  18  s  -69°15!6  S  -69°58!2  7  5  s  -69°28!4  24  s  -69°13!2  25  S  -70°24l2  14  S  -69°57!1  11  m  Declination  57  10  m  (1975)  16  m  18  m  49  S  -70°  2i  m  59  S  -69°56l6  24  m  43  S  -69°21\l  28  m  27  m  27  m  29  m  30  m  32  m  33  m  s 20  l!9  -70°2l!6  40  S  -69°  6!8  20  S  -67°23!6  46  S  -68°  28  s  -68°57\l  57  S  -70°12!8  34  S  -68°51!4  4l6  (1975)  Table I I cont'd L.M.C. F i e l d Star  #6 Right  Ascension  (1975)  Declination  1  5  h  0  m  24  S  -70°15!8  2  5  h  0  m  46  S  -70°39l4  3  5  h  I  28  S  -70°38.'2  5  h  2  m  4  S  -70°53!3  5  5  h  5  m  4  S  -70°3o!9  6  5  h  5  m  6  S  -70°27!6  7  5  h  6  m  14  s  -70°19:4  8  5  h  8  m  16  s  -71°  7.*8  9  5  h  13  s  -71°  K6  10  5  27  s  -70°46!l  11  5  8  S  -73°17l8  . 12  5  13  5  h  26  m  4  s  14  5  h  26  m  41  S  -73°  2!8  5  h  28  m  45  S  -73°  ^\(>  16  5  h  24  m  44  S  -72°  9l7  17  5  h  27  m  20  S  18  5  19  5  h  33  m  54  s  20  5  h  35  m  10  S  -71° l l A  21  5  h  37  m  12  s  -70° 58!6  22  5  h  38  m  0  S  -70° 4 9 ! l  23  5  h  38  24  5  h  38  m  58  S  25  5  h  39  m  19  S  26  5  h  39  m  16  s  4  15  .  .  m  m  11 15  h  h  m  16  m  32  10  8  - 7 3 ° 18.'2  S  40  -73°19.'8  "  -72° 12.'7 -70  14  53.1  -70 53!4 o  -72°  9.3  -7 2°  2*. 4  -72°10!4 -7 2°  5.'o  (1975)  Table I I cont'd L.M.C. Star  Field  #6  • Right  Ascension  (1975)  27  5  h  41  m  U  28  5  h  38  m  35  S  29  4  h  59  m  57  s  - 7 1 ° 1!  .30  5  h  2  m  29  S  -71°  4*  -72°30.7  S  9  h  (1975)  Declination  -71°36.0  <?  6  3!9 1  31  5  32  5  h  7  m  11  s  33  5  h  8  m  6  s  -72°49.'2  34  5  h  8  m  52  S  -72°47l3  o  '  h  9  m 10  -72 19.4 b  -73°  7  9.4  '  35  5  -72°17.8  36  5  h  10  m  32  S  - 7 1 ° 4 7 \$  37  5  h  13  m  36  S  -70°52.'5  ,37a  5  h  12  m  29  S  -70 50!3  38  5  h  12  m  49  S  - 7 1 ° 4 7 !7  39  5  h  13  m  50  S  -72°55!l  40  5  h  15  m  55  S  -72°33!2  41  5  h  14™ 4 4  s  -71°44.7  42  5  h  16™ 1 5  S  -71°52.'4  43  5  h  16  m  35  S  -72°14l2  44  5  h  18  m  32  s  -71°53!4  45  5  h  17  m  38  s  46  5  h  18  m  33  S  -70°57l7  47  5  h  20  m  21  s  -72°43l3  48  5  h  2 2 ° 20  S  -72°30.'5  49  5  h  22  m  13  S  - 7 2 ° 5.'3  50  5  h  23  m  26  S  o  - 7 1 °  •  4U  -71°59l0  .  -  Table I I cont'd L.M.C.  Star  #6  Right  Ascension  Declination  5  h  23  m  52  5  h  24  m  4  S  -71°47!2  53  5  h  21  m  34  S  -71°29.*8  5  h  23  m  5  S  55  5  h  23  m  44  s  -71°34:3  56  5  K  23  m  59  S  -71°27.'9  57  5  h  24  m  50  S  -71°26!o  58  5  h  23  m  44  s  -70°45h  59  5  h  24  m  56  s  - 7 1 ° 5!4  60  5  h  24™ 5 3  S  -70°59!8  61  5  62.  5  63  5  h  m  h  26  8  m  in  56  5  h  65  5  h  26  m  66  5  h  30  m  67  5  h  3i  68  5  h  32  69  5  h  33™  2  70  5  h  33  m  71  5  h  33  72  5  h  34  73  5  74  m  m  -7 1 25 .'6 . 0  S  S  s  27" 3 3  -7'p 58 !3 0  -70°55!4 o  '  -70 40.3  S  -70 40!5  26  S  -72°13.'5  47  S  - 7 2 ° 4!9  58  S  -71°44!5  16  S  -71 ll!9  O  0  s  -71°32!7  28  S  -71°34!.9  m  6  S  -71°27 !8  m  6  S  -71°23!o  h  33™ 5 3  S  -72° 4 ! 9  5  h  34  m  37  S  -71°59 ! 1  75  5  h  35  m  27  S  - 7 2 ° s!'7  76  5  h  38  m  4  S  (1975)  -71°44!5  s  27 34 28  h  11  (1975)  51  .54  ...  Field  -70°55!9  Table I I cont'd  L.M.C.  Star  Field  #7  Right  Ascension  1  5  h  31  2  5  h  3A  5  h  35  3  '  11  S  m  24  S  m  4 1  s  m  (1975)  Declination -65°33!2 -67°29.5 -66°21.8  (1975)  Table I I cont'd  L.M.C. Star  Field  #8 Right  Ascension  (1975)  Declination  1  5  h  44  m  33  s  -69°  2  5  h  48  m  21  s  -67°14.5  3  5  h  4 8  m  3  s  .4  5  h  5 2  m  42  s  5  5  h  25  S  -68°46!1  6  6  h  5  m  56  S  -69°27!2  7  6  h  7  m  41  S  8  6  h  7  m  33  s  -69°26.2  9  6  h  8  m  43  s  -69°58\h  10  6  h  7  m  23  S  -67°52l4  11  6  h  7  m  41  s  -67°52l0  12  6  h  8  m  47  S  -68°15'.9  13  6  h  9  m  10  14  6  h  io  m  53  m  50  8!6  -69°22!1 -67°54.5  S  -70  s  o  ' 31.0  -67°12l3 -67°16!5  (1975)  Table I I cont'd  L.M.C. Star  Field  #9 Right  1  5  2  5  h  3  ....  (1975)  Ascension h  5  *  4  5  h  5  5  h  6  5  h  7  5  8  45  m  45  m  47  m  46  m  48  m  48  Declination  (1975)  19  S  -71°35.2  24  s  -70°38.2  23  s  -70°33!5  49  s  -71°13l8  12  s  -71°13 ! 0 -70°58l4  m  6  h  48*  54  s  -71°42.'8  5  h  49  37  s  -71°39l2  9  5  h  4 9*  I  10  5  h  49™  13  s  11  5  h  4 9* 5 5  S  12  5  h  50  7  S  -70°59l5  13  5  h  31  S  -7 0 ° 4 5 l 2  14  5  h  45  S  -72°30!7  15  5  h  25  S  -72°2l!3  16  5  h  5 2* 3 0  S  -7 0° 36 .'5  17  5  h  s  - 7 1 ° 26.'5  18  5  h  19  5  h  20  5  h  21  5  h  22  5  h  23  5  h  24  6  h  25  6  h  m  m  50 5 l  m  m  52  m  s  -70°46!o  s  5 2* 4 1  -7 0° 44 .'8 '  -7 0°52.'6  53*  4  s  -71°35!l  53*  22  S  -71°37 ! 1  54  m  4  S  -70°25l5  54  m  23  S  -70°33 ! 3  54  m  18  S  - 7 1 ° 0.*5  21  S  -70°48!o  18  S  - 7 1 ° 1 1 \l  9  S  56 o  m  m  . 7*  Table I I cont'd  L.M.C. F i e l d Star  #9 Right  Ascension  26  6  h  5  m  27  6  h  6  m  28  6  h  29  6  h  12  m  30  6  h  13  31  6  h  32  6  h  33  6  h  34  6  h  19  m  35  6  h  19  m  36  6  h  l l  40  S  31  S  II  m  -71°lo!9  s  m  io  s  16  m  9  S  17  m  50  S  2  S  19  S  46  S  43  s  22  m  (1975)  -7 0°44*9  S  m  Declination -71°21!9  48  20  (1975)  -72°  3^  -72°lo!4 -71°44!2 -71°36!l -72°28 ! 6 -71°16l8 -71° 9 l 6 - 7 2 ° 3 7 !o  23  Table I I cont'd L.M.C. F i e l d Star  #20 Right  1  5  2  6  3 4  .  6 6  Ascension h  h h  57™ 9  m  14 18  m  24  s  ,, s  14  22  S  0  s  (1975)  Declination -73°52!4 -73°50.1 -73°53ll -74°  1.3  (1975)  Table I I cont'd  L.M.C. F i e l d Star  #23 Right  Ascension  1  6  h  2  6  h  3  6  h  4  6  h  5  6  h  6  6  h  7  6  h  8  6  9  io  m  ll  m  ll  m  12  n  13  m  13  m  13  m  h  15  m  6  h  16  10  6  h  11  6  h  12  6  h  13  6  h  14  6  h  15  6  h  16  6  h  17  6  h  18  6  h  19  6  m  16  m  17  m  16  m  16  m  16  m  16  m  m  18  m  h  19  m  20  6  h  19  m  21  6  h  19  m  22  6  h  23  6  h  24  6  h  Declination  (1975)  27  -68°27.6  38  s  -68°  5 !'3  56  S  -68°  3.7  45  S  8  S  -67°56!3  21  S  -67°49.'9  44  s  - 6 7 ° 2 8 !4  39  S  -67°28.9  18  s  -67°25!o  55  s  - 6 7 ° 2 9 .'7  38  s  -67°26!4  52  s  io  s  -68  31  S  -68  19  S  -67°34!o  - 6 7 ° 5 3 !o  16* 3 5 17  (1975)  S  0.5 o O  -68  »  3.5 I  9.1  S  7  S  14  s  21  s  26  S  24  S  15  S  20  S  o  s  -68°  9l4  -68°13 ! 2 -67°47!8 -67°49!8 -67°49.8  20  m  2l  m  22  m  -68°22!2 -68°27!8 -68°20.7 -68  o  «  0.6  T a b l e I I cont'd L.M.C. Star  Field  #23 Right  Ascension  25  6  h  22  m  26  6  h  22  m  27  6  h  23  28  6  h  23  29  6  h  30  6  31 32  10  m  Declination  S  o  -67  » 52.3  31  s  m  48  s  25  m  55  S  -68 10.'8  h  26  m  21  S  -68°46.'8  6  h  2 6  42  S  -68°49.'2  6  h  27  m  16  S  -68 °52!0  28  m  56  S  -68 °54!6  h  m  -68°35!9 -68°57!o o  33  6  34  6  h  3l  m  21  S  35  6  h  14  m  16  S  -68°48!8  36  6  h  l l  m  37  S  -68°52.'8  37  6  h  l l  m  57  S  -68 °58\l  38  6  h  13  55  S  -68 °58l7  39  6  h  l l "  54  40  6  h  13  m  24  S  -69 °14 ! 4  12  m  21  s  -69 °44 ! 6  50  S  -7 0 ° 1.'3  41  " 6  h  m  m  s  -69  o  » 11.1  -69°15.'l  42  6  h  11  43  6  h  13  m  46  S  -70 °13 ! 0  44  6  h  15  m  6  s  -70 ° 0 ! 2  45  6*  15  m  15  S  -70 °29 !3  46  6  h  24  m  47  S  -70 13.'6  47  6  h  24  m  39  S  -69°53l2  48  6  h  24  m  40  S  -69°44!l  49  6  h  25  m  5  S  - 6 9 °4 4 ! 0  50  6  h  2 9  3  S  -70°20l4  51  6  38  s  h  13  m  m  (1975)  -67 °59l4  s  2 6  (1975)  o  - 6 9 ° 2 8 !3  )  Table II L.M.C. Star  Field  cont'd  #24 Ascension  Right  1  6  2  6"  29  3  6  30  h  h h  26  47  m  n  m  S  . s  34° 42  s  (1975)  Declination -71°41.8 -70°55.5 -71°  0.6  (1975)  ....  F i g . 1 F i n d i n g C h a r t s LMC F i e l d #1  ».  . •„<"-*  />'<•*•*  ~  /  •I  \  .*." * *  •  .  •  T 7  I  ..  Y.^:r.'IS*.  . 0  . . . .  .•.-»  • •  • v rig-"* •*•«-•  F i g . 1 c o n t . LMC  Field  #1  N3 00  29 y.yr^i.VVJ-'mrv,  • ...  ....  it* "  *v% -.-,* • ~  -  ••  5  ,  • ••  ••• *v '••••  .  '  •  •  *  r •  sr..'-  Si,  V  - - "v"*?  r  v"' •'" • • • ' 4  ' V.  sis y> *  .v* f *  *  matt  %-»W4  / . .  • •  •  . !  .  •  •'•*••»• . ' - ' * • • . %*.m ". - -'it ' >••>:" •' v  '  z  .. . • - • »• , ;••  •  * 4  rH OJ •H U  a 4J C o  o r.- <  »t • •H •  •  j  • ,  \*sj"'**»••'.  ?» o  7*J?*  - ••  •••• ' V . 5 i  • * •'- »*:•>  co o  F i g . 1 c o n t . LMC F i e l d  //l  V  F i g . 1 c o n t . LMC F i e l d  #2  H  .v  Fig.  1 c o n t . LMC F i e l d #2  S3  !.\'-;-  > vti V  :  •••• V  ' - A  ..  .•'«."•""  '.''..•>-v^', #  • • *  i  : J ••" v  •  '.'  ..•*•...••  '•*.•* v i  v  * •  • v. •  • *< i • •.  .-  . .• •  ... •-  Fig  0  1 c o n t . LMC F i e l d  #3  ft'.  F i g . 1 c o n t . LMC F i e l d  //4  u> 0 1  1  ' *  •  !  •  •j ~ "~ -  <  1  *. . *  •  •  •  .*  •  t •  . • • -  .  .  •  B» •  •  f. • i  •*  '  V  ,• '' •  • '"^  . i  •  ... *  I  • *  SI  «  • 1  Ms*.  r y  '3  I •  16*.  ©  1 •  k-  I,. • / U) F i g . 1 c o n t . LMC F i e l d #4  ON  F i g . 1 c o n t . LMC F i e l d #4  39  ' r**» ••">•»  l»- S r * • « -  *  •  $4*I • i fe  .  •  . »  -V'] •Bill rlJMiiTT  Tin'ii_mjj  =&  5kV*;  H  . •'•>!  •H  a o o  iff"*  1,  >•< "  t  k  :  ...  .  • ' • • • . * * * '• •  ••••  *  to  -7  «  • "  •  •a ' :  ' t -  4  • .,  •  «.»,"» .A* : • 't.  i  *-»....  •. ***•. ,:  r  • • • .. ^ • • • •  - ••  / • >,  .v • • %  v- * ; hO''"  • •••• «i  •• •  •>.  '••••'•3  •»  -  •••V• * '--ii ••••  • K  ;  • . .t  if:.  trim  .  • V 4*.-.' . i.v. 1  •.. .  * * *•  1  • "  I  N .  «,*t. * vasrWi?*J  pre  •  '  •  •  •  k*.*H>. i . * A  JVC* k - * .  Ax  ft k s i  \  »  *  «• ta ^  • / < • •^ * -  »  3».'  Be'  •••• r.*^>^-:;i:;<? ••••••  • « *>r  . v *, . .f  - J"- . • * V » -t  ,  r.j>t. 0 * IL"  F i g . 1 c o n t . LMC  Field  #6  •  7,  a) •rl  •  *  . • <.,v-....  *4  *.  o » » •».•*  a 4->  c  o o  to  F i g . 1 c o n t . LMC F i e l d #6  i  -'V-.. '*.-  '•* » f  •••• •  t m - yryv<w» a'i — ,  ^ •  1- T>1  »  *. • •  •••• *  .  7  1  •  *  .e * ** * " ..• ° »»a  •• •  .....  \v  ."6.  ' *.i • •  ..  •;  . - »*i  .  •'  ' •  .'  .  •• • , • . :': -  ;  •  •V.  F i g . 1 c o n t . LMC F i e l d #6  .«v •  • , iff Jf  •  '•.  '  .•  •  47 J  :  //v .1  y  I • •  ir. •  «...  .  : •  •  '•*.•: » / • ' • ' " > ' .* v Li » ? ' \>"J* .» •  •*- f  •  .  •  <\ :  •  #  ;  . ' • •  t - . * u•: .  *  '  •  V '  •  •A  W.1  ' :  :  :*f  .-••»•*, . »  • .'*v.. •• * *  •.  *  •H fe  L  '  y - ...  . \ -c. - * * • • * . . . • •  »•  v  • r  1  " ' .*' %  «,  • ... •' .»>.. . ".•  •. • *•  • >  .. • •  WD  '  :-ml  *  o a  PH  v  «  4J  • H  ;.. :.--.....".v..^ .v •..  2  6.0  >v:,  i •••• ' •Lr* .'T 'v  CJ  i-l  . - *.^**YYY  .<"••>:••v•:v>1 / *  Y  ' ^ Y  Y  Y  •V*" ,  M  ' •  . ». . .  .Y •  v A. ,S7Y'  4  • Y  'i,  •Y.^>*  •» ,  c  -T-:; >  V ".V^:  »A.- Y - ' : i . Y Y - : j  V  Y.  .-V  V\  V-  .Y.'-'  %  .«8  •4  '. Y  •q  ;>•:• ,v V*<i  #  V  Y. -v\-r-:-YY :  *• ^  <Y;Y  v...f  tSUkj.  Fig.  i.4liJ<!  1 c o n t . LMC F i e l d #6  0(9  49  F z -'' • * • i . " • • *  ••.  »?  •  •  '  ...  *  %  i  .1 •  I/* a.  .*:  jr.. * • -•X.'  •  -* ..-. ,  p  •t • * *  "• • • '  '•- * » V  • •• * , * " ?•>. *  i  5  * * V  * z*<v  " -' •  - * M•  ;  *  . f ; - ...» •>•• *;/^f3  t • „ ••  i  ••••• ' . •.  r  .V  •' • • ' i . . - . : - . v  .  '"•  :  V  v  I ....  v • ; . • • <  a 9  v  ^h'iv^.<y  '  • .r>-.-:; ,  '  V .  •  :J>i-.;--;...;•>;/<  KM '•• •*-*;/  v. • - i . - . fey ; * c ; v ^ V ; r -X.. r- '  K  V  -  .  *  ' K i '*-•' « •  "  F i e . 1 c o n t . LMC F i e l d #6  o  i  F i g . 1 c o n t . LMC F i e l d #7  Fig.  1 c o n t . LMC F i e l d #8  *  A • • •»  I'.'  *  ,  '.  . .1."!  ' '  2-  •y «...  fa*-  «  ••'  /•  •".  •  £>\ ••'•'.*''.'-v3  •  :  .  ' ! ' • ' » • . - '  •  I  ,•• '•V-' •  .V- •••  •  ..V  f *  t  i  >  •  '  -  . : . . . . • 5.  Y'->:'-' :/  V  v : W-TV:  t  V':' •••  * Y. =  ,;v3v. > .  1 F i g . 1 c o n t . LMC F i e l d  #9  "-."..rrv  i  F i g . 1 c o n t . LMC F i e l d #23  64  • Y.-«  •.•vi  E  •• • • i  t *  f.  -  ft-;*:,-  •••'•^Y^-T!\>.!^gwiw»^  ^"*'Y:  ;  I- • •  t~K-:, w% i • ,* r r fe'*-  • •'  *'  M  -  i *  . • Y  f  •Y4  l" • * *) ' •"* •  p  5  •  ••Y  Y  - Y  fv;  | • .:* 1•  it * k " '  | •• • Witt* j  '  • '  '' * " .  *  J  * • '• •:  -• v  *  Y •.. • j  1  Vio.  1 r n n t .  T.MH F i e l d  #24  S  66  I i i £]l££2J§££ic O b s e r v a t i o n s  The  absolute  known.  No  carbon  trigonometric binary  magnitudes of carbon star  parallax,  systems  forementioned  and  facts  magnitudes - f o r  they  that  the  The  absolute  are seldom  be  photometry  on  Cerro  of on  was  Tolclo  the  members  Large  stars  of  A l l the  VRI  the  visual  known  i n the To  the  in  the  stars  system.  with  the  one  n i g h t s o f Dec.  17-22  1974.  stars  which  were  observed  w i t h comments f o r some of t h e s t a r s .  other  star  spectra  for  V  taken was  standard  calculated  only  only  were  photometry seven  stars  the  R-I  c o l o u r was  and  V-R  was  will  be  calibrated stars,  obtained.  on  each  in  stars  Section  night using  extinction The  The  and  average e x t i n c t i o n  in  communication).  previous The  coefficients  agree very  observing  average  rms  one  for  which  IV.  The  an a v e r a g e  of  were  coefficients K (S-1) =0.088.  well with  runs(Olson,  deviation  For  for  coefficients  n i g h t s were: KM=0.111, K (V-R) =0. 024,  These a v e r a g e e x t i n c t i o n obtained  obtained  discussed  and  f o r each n i g h t .  the three  data f o r a l l the  metre  photometric  of the  Large end  I I I c o n t a i n s the  two  so  this  Table  along  of  Magellanic  enough  determined.  obtained on  reliable  to obtain absolute  forty the  have a  poorly  in clusters.  carbon  accurately  have been o b t a i n e d  telescope  of  very  rarely  However  magnitudes  can  to  are  found  are  i t s distance i s well  measurements  VRI  stars  objects.  i s n e a r enough and  catalogue  enough  make i t d i f f i c u l t  Cloud  photoelectric  near  carbon  these  M a g e l l a n i c Cloud  is  stars  f o r the  those  private standard  67  Table I I I  STAR  V  Carbon s t a r  V-R  V-I  photometry  COMMENTS  1-1  16.34  2.53  3.49  1-2  16.06  1.87  3.36  1-4  16.35  2.77  4.16  1-5  14.20  0.43  1.72  1-9  15.68  2.19  3.42  1-10  15.42  2.15  3.50  1-11  R-I  1.25  1-12  13.87  1.14  2.00  1-13  16.09  1.92  3.16  1-14  15.71  2.28  3.49  1-16  14.72  0.28  0.39  1-18  15.86  1.88  2.71  1-20  15.57  2.12  3.33  1-21 '  16.18  2.23  3.68  1-22  16.17  2.24  3.34  1-23'  16.08  2.42  3.72  4-1  15.84  1.80  3.05  4-2  _15.74  2.17  3.46  4-3  16.69  2.74  4.12  4-5  15.99  2.17  3.53  4-6  16.80  2.62  4.16  Perhaps i n a nebula?  4-9  15.77.  2.03  3.49  Spectrum obtained  4-10  16.02  2.31  3.74  6-1  16.09  2.82  4.24  6-2  15.70  2.03  3.38  6-3  R-I  6-4  15.29  2.07  3.29  6-5  15.53  1.78  3.04  6-6  14.27  1.33  2.32  6-9  15.47  2.17  =  Not a carbon s t a r  •  Spectrum obtained  Not a carbon s t a r ; spectrum  Spectrum obtained  1.56  •  3.34  Spectrum obtained  Spectrum obtained  68  Table I I I cont'd  V-R  V-I  15.69  2.03  3.36  6-13  15.73  1.86  3.03  6-14  15.61  1.90  3.14  6-15  16.30  0.39  6-16  14.94  1.67  2.90  6-17  15.35  1.91  3.16  6-18  15.91  2.33  3.72  6-19  15.65  2.37  3.67  6-20  15.84  3.05  4.37  6-21  15.48  2.27  3.57  6-22  15.39  2.06  6-23  16.45  6-24  STAR  V  6-10  COMMENTS  Not a carbon s t a r ; probably wrong s t a r i n d i c a t e d on chart  Perhaps i n a nebula?  3.17  Spectrum obtained  0.54  2.21  Not a carbon  15.49  2.09  3.37  Close companion 6" north  6-25  15.47  1.85  3.10  Spectrum obtained  6-26'  15.84  2.34  3.57  6-27  15.20  0.69  1.88  6-28  16.01  1.97  3.27  .  Not a carbon  star  star  69  s t a r s was  0.04  both of the  With  magnitudes i n V and  about  0.03  magnitudes  colours.  this'  sample  of  forty  carbon  stars  f o r which  a b s o l u t e v i s u a l magnitude i s known to a f a i r degree of a r e l a t i o n s h i p between absolute magnitude and can  be i n v e s t i g a t e d .  working  with  a  However one  restricted  these f o r t y s t a r s are on carbon s t a r i n the fact  that  only  observations.  visual  while the  a  one  This  has  modulus  -1.7  sample of s t a r s , i n the sense  that  than  the  average  This a r i s e s from  telescope  was  used to  2  brighter  b r i g h t e s t carbon s t a r observed i n apparent v i s u a l magnitude of  the  16.80.  Large  I f one  Magellanic  absolute v i s u a l  Cloud  magnitudes  are  stars  S-I.  are  I t can  be seen  that  in  general  a l s o the redder s t a r s , although the  mean l i n e i s g u i t e  large.  hourglass  symbol  be d i s c o r d a n t with the r e s t of  are in  seems  It i s possible  to  separated from the These two  One  star,  that t h i s s t a r i s net  other type of red g i a n t .  (B-I),  a of -4.6  The  bulk of the  s t a r s are  two  marked  s t a r s by about 0.3  carbon  stars  by  a carbon s t a r  s t a r s marked by  as  the the  scatter  around the  some  13.87  assumes  i s a p l o t of apparent v i s u a l magnitude versus  photometric c o l o u r ,  sample.  the  make the  o b s e r v a t i o n s to the  a magnitude of  the  that  respectively.  Fig.  fainter  an  to  18.5 (westerlund 1972) and  are  r e s t r i c t e d the  region  accuracy,  we  metre  The  the  various parameters  remember  Large M a g e l l a n i c Cloud.  f a i n t e s t has  distance  must  the average b r i g h t e r  members of the c a t a l o g u e . the  for  the the but  diamonds  magnitudes  spectra  were  V v e r s u s R-I  F i g u r e 2.  A A  A  A  A  A A  A A  A  A A  A  A  X  A_\  A ^ A A  A  A A  z^A  A  A  A A  A  <!>  0 D.B  1.0  1.2  1.4  R-I  71  Figure  3.  V v e r s u s V-I  CD  A A  10 LO .  A  A  rv  A  LO .  A  ,  A  A  1  A  A  A A  CO  i n —1  A  A  A  A  A  A  &  ^  in  A  in.  A  LCI  -a".  ca rn  1 .B  2.25  2.7  3.15  V-I  "1 3.6  4.05  4.5  F i g u r e A.  V v e r s u s V-R  73  obtained  of  both  of  these.  However such warm b r i g h t carbon  s t a r s are not known i n our Galaxy.  I t i s p o s s i b l e t h a t they are  high l a t i t u d e CH-stars although the r e d s p e c t r a a v a i l a b l e do not allow a d i s t i n c t i o n t o be made between l a t e and  CH-stars.  In  this  case  verify this possibility. spectra  type  carbon  blue s p e c t r a would be needed to  I f these s t a r s were CH-stars then  4  are  the  independent  mentioned  Figures  same  type  variable  respectively. in  relationship  has  The  same  Fig.  2.  changed  symbols - In  to  (V-I)  have been used  these  latter  two  not  that  near i n f r a - r e d  any  From these t h r e e diagrams  tight  correlation  5  shows  a  plot  the  carbon  corrections  used  correction  stars were  in  those  this found  the  it  red  sample. by  correlation  and photometric c o l o u r .  c l a s s I I I g i a n t branch.  normal  the  does  can be found between and  The  Olson and between  The s o l i d  r e p r e s e n t the mean l o c a t i o n of the Ib s u p e r g i a n t branch  form  stars  of absolute bolometric magnitude  Richer (1975) i n t h e i r i n v e s t i g a t i o n of the bolometric  f o r the  colours.  (V-R) • f o r  bolometric  the (V-R)  diagrams  v i s u a l magnitude and photometric c o l o u r index f o r  Figure  and  3  between magnitude and c o l o u r i s not as t i g h t as i n (R-I) diagram*  appear  of p l o t s as i n F i g . 2 o n l y now been  the V versus  versus  the  would be expected to show enhancement of the G -band as  w e l l as enhancement and  stars  and  lines the  The carbon s t a r s i n t h i s sample seem to  q u i t e a d e f i n i t e branch between the Ib s u p e r g i a n t s and the giants.  artificial  as  However the  this  appearance  may  be  sample of carbon s t a r s i s somewhat  somewhat brighter  75  than average, as l e a s t to  say  bright  i n the v i s i b l e r e g i o n .  I t would be  safe  that the c o o l carbon s t ars seem t o cover the range from giants  magnitude.  to  ordinary  g i ants  in  absolute  bolometric  76  IV  S£ectrosco£ic Observations  Carbon s t a r s ' e x h i b i t one astronomical  object  in  of the most complex s p e c t r a of  the v i s i b l e and  T h i s s p e c t r a l region c o n t a i n s well 1 2  as  the  C i * N , C C , * C H and 1 2  l 2  bands  the other  2  near i n f r a r e d r e g i o n s .  a multitude  absorption  any  of  of  atomic  such  lines  as  molecules  as  i s o t o p e s of these s p e c i e s .  has  always  hampered  The  complexity  of t h e i r s p e c t r a  attempts  to  interpret  t h e i r s p e c t r a i n terms of temperature, l u m i n o s i t y  and  abundance e f f e c t s .  Any  attempts to c o r r e l a t e l u m i n o s i t y  have been hindered sufficient  sufficient  it  is  other  accuracy  possible stars.  Cloud  are  good  of  carbon  given  carbon s t a r .  to  absolute  differing  magnitudes  of  from  the that  of  in  the  Large  Magellanic  f a i n t a l a r g e t e l e s c o p e i s needed to get a "large  luminosity  sample  effects.  The  s p e c t r a at a d i s p e r s i o n of 117 of the  1.5  these  main  molecular  note some of the g r o s s e r f e a t u r e s i n the  the image tube spectrograph  of  to confirm  carbon s t a r s , by observing  Slit  because of  do t h i s f o r carbon s t a r s as i t i s f o r most  s p e c t r o s c o p i c i n v e s t i g a t i o n was indeed  magnitudes f o r a  T h i s of course assumes  Since the :carbon s t a r s  spectra  investigate  and  features  known to determine the l u m i n o s i t y  relatively  slit  stars  There'are j u s t not enough  spectrum of any  spectral  by the l a c k of good absolute  number  abundances.  and  stars  purpose  to  of  my  that the o b j e c t s were i c * C bands, and 2  2  to  spectra.  AVmm were obtained  meter t e l e s c o p e  at  with Cerro  77  Figure  6(a)  Carbon s t a r s p e c t r a , r e g i o n  1  Figure 6(b) Carbon star spectra, region 2  79  T o l o l o i n December 1974. the  use  of baked H a - 0  the system.-  on the order  The of  o b s e r v a t i o n s are image  phosphor of the image tube  p l a t e s to g r e a t l y i n c r e a s e the  In g e n e r a l the  5000A-8000A.  an  The  spectral  range  covered  hundred  found  minutes.  i n t a b l e IV.  The  speed of was  f a i n t n e s s of the o b j e c t s d i c t a t e d  one  allowed  from  exposures  details  of  the  On such long exposures  with  tube the number of i o n events becomes s i g n i f i c a n t  and  hence the background fog l e v e l becomes q u i t e high.  Table IV  I  E.A. (1975)  | Star  Spectroscopic  Dec.(1975)  Observations  Date (U.T.) Exp.  Time  I J  1-12  5  03  11  |-66  02.9  | Dec. 1 4 / 7 4 J 91  |  6-25  5  39  19  | -72 10.4  I Dec.14/74 | 85  |  1-20  5 00  26  1-65  02. 5  JDec.15/74  |118  »•  5 05  06  1-70  27.6  |Dec.15/74  J 92  "  i 123  I  6-6  |  6-22  5 38  00  1-70  49. 1  |Dec.16/74  |  4-9  5  17  10  |-64  48.5  | Dec.  |  6-4'  5 02  04  |-70  53. 3  |Dec.16/74  Spectra of e i g h t these(star  1—16)  showed molecular showed  a  stars  was  were  not a carbon  bands of C ^ a s  great-range  »  The  "  |10 4 »•  and  only  w e l l as bands o f CN.  The  i n the s t r e n g t h of the molecular  only one  one  other seven  w e l l as i n the s t r e n g t h of the D - l i n e s of sodium. Hc^in a b s o r p t i o n and  11  16/74 |91  obtained star.  min.  None  of  stars stars  bands as showed  showed a t r a c e o f emission at H«=»< .  80  Emission  at  In g e n e r a l  H"°^ i s t y p i c a l  the  only  Tracings  of  850-6950A the  produced  the  are  interval  atomic  by  lines  digitizing  to  the  Joyce-loebl•Microdensitometer  point two  The  triangular  Large  relative  to the  sun  due  to  solar  motion.  star  i s a probable  the  radial  velocity present  heads  I  had  for  the  a • member several and  standard  of  band  :after  of the  rely  velocity  should the  Large  heads i n t h e correcting  wavelengths  a  nine-  comparison,  velocity  by  this i s  measuring  serve  atomic  of the  the  i n d i c a t e whether o r n o t  G a l a c t i c carbon motion  produced.  stars of  The  definitely D-lines  This  The  the  radial  molecular  velocity  Cloud.  as  lines  s t a r s were t h e  measurements.  the  the  same manner.  just  to  position  Magellanic  for was  or n o t  only  more e r r o r i n t o still  i n the  on  S e v e r a l s p e c t r a of G a l a c t i c  Cloud  on t h e  For  were  t o a s c e r t a i n whether a  night  s i n c e the  with  Almost a l l o f  one  shows  Astronomy  systematic  - 1  each  6(b)  and  noise.  a  H°<.  interval  intervals  smoothed  kmsec .  star.  Magellanic  introduces  result  5/c  was  has  and  tracings  Geophysics  This enables  and  to  radial  about 250  Figure  These at  data  Variables.  D-lines  while  to reduce the  obtained  i n the Large  admittedly but  were  standards  sodium,  of the  member o f t h e C l o u d  velocity  stars  spectra  M a g e l l a n i c ' Cloud of  Period  wavelength  s t a r s were a l s o r e d u c e d  The  carbon  the  ^5900.  resulting  filter  G a l a c t i c carbon  over  i n F i g u r e 6 (a)  ^5000  D e p a r t m e n t a t OBC.  c a r b o n Long  s e e n were the  spectra  shown  from  of the  of band  procedure measurements the  star  is  wavelengths of were  measured  earth  a set  positions  of  of the  81  corresponding stars  band  were'then  heads  i n the Large Magellanxc set  of  velocity  was  found  after  correcting  f o r the e a r t h ' s motion i n the d i r e c t i o n  of the  Large  Magellanic  'Cloud;  The  other p e r t i n e n t parentheses  the  final  quantities  is  to  radial  f o r the seven s t a r s .  the probable e r r o r  systematic  standard  The r e s u l t s are shown i n Table V a l o n g  v e l o c i t y of 2 4 5  average  relative  carbon  this  wavelengths.  measured  Cloud  kmsec  -1  Ihe  with  number  in  i n the r a d i a l v e l o c i t y .  i s in excellent  v e l o c i t y of the Large  agreement  Magellanic Cloud  The with  found  by  Bok ( 1 9 6 6 ) .  Table V-groEertj.es of the Seven Carbon S t a r s ir  T  —  H  | Star  | Vr (kmsec-*) i „_ i  ,.  ~|—  —r  "T  | V-R  | V-I  !  j  !  j 13.87  |1.14  I2.00  1  v  1  T"  Mv | Mbol  J  | 1-12  1  344 (17)  | 6-6  |  346(66)  J14.27  I  I6-4  I  198 (50)  |15.29  | 2 . 07 | 3 . 29 1 - 3 . 2 | - 6 . 6  16-22  |  189 (34)  115.39  | 2.06 J3.17  1 6-2 5  |  198 (43)  115.47  j 1. 85  | 1-20  i  190 (38)  | 15.57  I 2 . 12 I 3 . 3 3  |4-9  j  253  | 15.77  j 2 . 03 13. 49 1 - 2 . 7 | -6. 0  .„ i,.  L  The  X  tracings  characteristics F i g u r e 6 (b). Night  (17)  sky  of  inthe  1.33 J 2 . 3 2  j._  Figure program  lines  are  indicated  J-3.1 | - 6 . 5  1-2.91 - 6 . 5  •i  show  marked  by n.s.  i  the  s t a r s quite  Prominent f e a t u r e s are  -6. 0  j-4.21  | 3 . 10 l -3.0 1 - 5 . 8  -. j .  6  1-4.61 - 5 . 7  carbon  well, on  star  paricularly  the  while p l a t e  tracings. f l a w s are  82  marked  by a d o t .  Table  by Y a m a s h i t a ( 1 9 7 2 ) measure These  for  lines;  = i2Ci C  C  i3 i4N  Li-  LithiumI  band  at  Star  determined with  by  with  as  an  comparing  intensity  the  ones.  13=i*Ci3C ^ n d b  band  defined  on Y a m a s h i t a ' s s c a l e .  the G a l a c t i c  )*6260; C N = " C i * N  at  X5730  ; H«< — X6563) A d i s c u s s i o n  star  Table  o r band  bands a t XA5636,6T91;  6708  individual  together  line  carbon stars z  A  and  C  were  the C - c l a s s i s i c a t i o n  star  specific  intensities Cloud  each  f o r each  each  Magellanic  VI g i v e s  (D=  Large Na  D-  at X6168  and  ^6206;  of t h e spectrum of  follows.  VI C l a s s i f i c a t i o n  C-type  D  C  ]  z  I  o f Carbon  Stars  13  CN  Li  j  1-12  -  1-12  C4,2J  4+  j 2  4+  2  0  0  6-6  C4,4J  4  | 4  4+  3  0  0  6-4  C6,3  6  i .3+  3+  3+  0  e?  6-22  C6,4  6  | 4  3  3  0+  0  6-25  C4,4  3+  | 4  3  3  0  0  1-20  C4 5  3+  | 5  3  3+  0  0  4-9  C 4,4J  2  | 4  5+  3  0  0  f  This s t a r the  was  stars  the b l u e s t observed.  characteristics Gordon (1967)  as  with  and It  defined the  brightest(in shows by  i3Ci*N  V)  o f any o f  moderate  Bouigue(1954) (4,0)  band  J-star and  a t )\6260  83  slightly at  s t r o n g e r than  )i6206.  strength (0,2) and  The  but the  (2,4)  lines  (0,0) band o f  2  2  -  are present  This star being (0,1)  was  the  with  second  very  well  12C12C,  1 Z  C  1 2  band  seme s t r e n g t h but L i  wavelengths  as i s t h e  l 3  C *N(4,0)  relatively  these  band  1  high  at  abundance  there  band(probably  SiCjJ  D-lines  quite  (0,0) and and  are of  but  weak.  features  are  The  ^6260,  of  are  i s present  * C. 3  * c*3C 2  implying Although  shortward  a t ^ 4977 .  s t r o n g but they  In t h e s p e c t r u m o f t h i s (0,0)  as  of  a the W  i s an i n d i c a t i o n t h a t t h e M e r r i l l - S a n f o r d  T h e r e i s no t r a c e o f e i t h e r  -  used.  sequence  respectively.  s p e c t r u m i s somewhat weakly" e x p o s e d  6-4  \ 6 7 0 8 and  as w e l l  present  D-  X6168 i s p r e s e n t w i t h c o n s i d e r a b l e s t r e n g t h  at  5000 A  (1,3)  Sodium  The  +2  (2,4) , i s  ^6060  the  strong  The  of  The  a t the r e s o l u t i o n  are moderately  defined.  ^ 6 1 9 1 , \ 6122,and  The  b l u e s t one o b s e r v e d  (0,2) , (1,3) , and  The  weak.  while  brightest visually. C  band  l  2  b u t weak.  not present  the next  bands o f  C +N  i C " C i s o f moderate  i s barely v i s i b l e  bands a r e p r e s e n t  H<*> a r e d e f i n i t e l y  6-6  1 2  (0,1) band i s s u p r i s i n g l y  i ci C  band o f  the corresponding  H  star  or  the  The  sodium  a r e not r e s o l v e d .  Li/\6708.  IZQIZQ  (0,1)  and  bands a r e weak t o moderate i n s t r e n g t h w h i l e t h e  84  (1,3)  and  (2,4) band heads are much s t r o n g e r .  i s a weak t r a c e of i z c from  ^6260 to  implying l 3  C.  a  The  strength  1 3  ^6168  C *N  are  the  present  (4,0)  and  appear to be s t r o n g l y enhanced.  6-22 -  The  1 2  the  region slightly  higher than normal abundance of  bands  J  although  present at  and  ^ 6285 seems t o be depressed  somewhat  l 2  C at  There  with (6,2)  moderate band heads  Weak e m i s s i o n may  .  C C(0,0)  and  1 2  (0,1)  bands  are  of  moderate  s t r e n g t h and are q u i t e w e l l d e f i n e d i n t h i s s t a r . 1 2  G  1 4  N  be  bands are w e l l developed  average s t r e n g t h .  and  saem  to  be  The of  The two* Na D - l i n e s are r e s o l v e d and  appear t o be of moderate s t r e n g t h .  The L i  ^6708 l i n e  appears to be present with c o n s i d e r a b l e s t r e n g t h along with  the  KI  line  at  ^7699.  There i s a l s o a band,  degraded t o the r e d , with the band head 6380.  This  band  Cas, a p e c u l i a r  at  about  ^  a l s o appears i n the spectrum of wz  Galactic  u n i d e n t i f i e d (Catchpole  carbon  1S75).  star, The  but  remains  i£C* C bands are 2  s t r o n g e r i n 6-22 than i n WZ Cas while the  Na  D-lines  are weaker.'• The abundance of * C i n t h i s s t a r appears 3  to be normal.  6-25 -  The  sodium D - l i n e s are present but weaK. while most of  the i c 2  l 2  C  bands appear to be  of  moderate  strength.  85  The  abundance o f  1 3  C seems t o be normal as t h e C i 3 C l 2  band i s present but very weak and the ^ c ! )  band  1 4  )S6260  i s not a t a l l v i s i b l e . .  V  at  Neither L i ^6708 nor  He* are present.  1-20  -  A l l the C > C 1 Z  bands  2  developed. abundance  i n this  star  a r e very  The +2 seguence i s e s p e c i a l l y s t r o n g . of  l 3  C  3  v i s i b l e but weak.  This  bands.  The  most  moderate  o r JP< .  high abundance of  d i s p l a y e d by the s t r e n g t h of  the  outstanding  i2C  1 3  C  and  3  corresponding  1  weak. the  i 2  The C  1 2  C  l 2  C  l 2  3  3  (0,2) should  a  t  l3  C *M l  X 6260.  X 6206  1  i s p r e s e n t but  band a t ^5636 i s very  strong  but  i c 2  1 3  C band a t ^6168.  There may be two  bands present, t h e (1,3) band a t "X6080 and the band at)\6145. ,be  The Na D - l i n e s are weak but  considered  i n l i g h t of the f a c t  absorption  from  i2c  l 3  G  and i c 3  l 3  this  t h a t the  e n t i r e r e g i o n frcm ^\5750 t o ^6150 i s depressed to  C as  band a t X&191 i s a c t u a l l y weaker than the  corresponding i cn C  C  I2QI4JJ  1 3  feature i n the e n t i r e  spectrum o f 4-9 i s the(4,0) band of i c * N a t The  is  l3  The sodium D - l i n e s are of  s t a r shows an extremely  1  ^6168, *zc C,  s t r e n g t h and there i s no t r a c e of L i ^ 6 708  -  The  appears t o be normal as t h e i c * N  band a t ^6260 i s not v i s i b l e while  4-9  well  due  C as i s the case  f o r the more extreme G a l a c t i c J s t a r s (Yamashita  1972).  86  It i s also possible l i n e at  All  that t h i s s t a r  shows  a  weak  KI  Cj,.  It  ^7699.  of the s t a r s above d i s p l a y  molecular bands of  i s perhaps s i g n i f i c a n t that three of the seven show h i g h e r normal  abundances  of •• G .  T h i s i s p r o p o r t i o n a l l y more s t a r s  13  than f o r G a l a c t i c carbon s t a r s . of the  s t a r s show d e f i n i t e H~-  of the  Long Period  are  not  members-  of  peculiar  spectroscopically  I  latitude  the  high  section  CH  O J C e n t a u r i by  will  Magellanic Cloud.  none  e m i s s i o n , which i s c h a r a c t e r i s t i c  the two  actually  s t a r s found i n  I t i s also suprising that  Variables.  I t i s possible that 6)  than  b l u e s t carbon s t a r s ( 1 - 1 2 and Large  stars. and  Magellanic These  Cloud but  stars  are  In  the  assume that a l l seven are members of  are  mildly  bear some resemblance to the  Dickens(1972).  6-  CH  following the  Large  87  I Carbon S t a r s i n the H-R Diagram  The is  not  evolved  precise evolutionary presently objects  nucleosynthesis evolutionary  phase (or phases) of  understood. which  in  exhibiting  spectra.  s t a t u s from data  stars  They are b e l i e v e d to be h i g h l y  are  their  caroon  on  the  Besides  masses,  products  determining  ages,  of their  spectra,  and  atmospheric abundances, one would l i k e to know t h e i r p o s i t i o n i n the  H-E  diagram.  The  comparing t h e o r e t i c a l -  H-R  diagram  models  with  determine an o b j e c t ' s e v o l u t i o n a r y  In  observations  useful f o r  in  order  to  status.  order t o p l a c e an o b j e c t i n the t h e o r e t i c a l H-R diagram  i t i s necessary t o know the well  has been very  as  absolute  bolometric  magnitude  the e f f e c t i v e temperature of the object.  as  First I will  address myself t o the problem o f f i n d i n g the absolute  bolometric  magnitude of a c o o l carbon s t a r .  bolometric  magnitude  of  an  object  d i s t r i b u t i o n over a l l emitted  by  by  to  a  f a r out  good  into  the  total  the  photometric  energy  observations  I t i s f o r t u n a t e that t h e i r r e s u l t s between  the  calculated  bolometric  (V-R) c o l o u r index f o r both R and N s t a r s .  Olson and Richer(1975) have i n v e s t i g a t e d find  the  the i n f r a r e d where most of the carbon  correlation  c o r r e c t i o n - and  find  observed energy  Mendoza and Johnson (1965) have done t h i s f o r  s t a r ' s r a d i a t i o n i s emitted. show  the  the  However t h i s can only be done f o r the  a few dozen G a l a c t i c carbon s t a r s , with extending  find  integrating  frequencies  the' object.  brighter objects;  One can  relationship  shown  in  Figure  this 7.  c o r r e l a t i o n and There  are two  88  F i g u r e 7. B o l o m e t r i c  •  N - s t a r  ©  R-slar  corrections  •~5>  ? y /  /  0/  e / / o  /  © s  V-R  2  89  d i f f e r e n t r e l a t i o n s shown; one f o r the R s t a r s and one f o r the S stars.  Since the R s t a r s are much f a i n t e r ( a b s o l u t e l y )  N s t a r s i t i s expected Large-  Magellanic  that a l l the carbon  Cloud are N-type carbon  s t a r s observed stars.  b o l o m e t r i c c o r r e c t i o n s f o r N s t a r s were used. where  the  Galactic.  stars  N  star-  than  the  i n the  T h e r e f o r e the  In  a  few  cases  were  slightly  bluer i n (V-B) than the b l u e s t  used  in  calibration  the  the  bolometric  c o r r e c t i o n was c a l c u l a t e d by simply extending the l i n e a r p o r t i o n of  the c a l i b r a t i o n curve f o r N s t a r s t o f i n d the c o r r e c t value.  I t i s expected  t h a t the b o l o m e t r i c c o r r e c t i o n s are good to about  0.3 magnitudes. obtaining two  have  F i r s t , there  of  the  Large  Second, any reddening stars  neglected  along  the  is  visually  very  little  Magellanic  reddening  calibration  but  will  curves will  i t will  in  stars for  reddening  Cloud (Bok  which i s present  T h i s i s because'the reddening fainter  interstellar  the a b s o l u t e b o l o m e t r i c magnitude f o r these  reasons.  direction  I  i n the  and Bok 1972).  tend  to  move  the  r a t h e r than a c r o s s them.  cause also  the  star  increase  to  appear  the b o l o m e t r i c  c o r r e c t i o n , hence the two e f f e c t s tend t o c a n c e l out.  The carbon  problem of a s s i g n i n g e f f e c t i v e temperatures  s t a r s i s not  as  easily  bolometric' corrections. which  radii  have  occultation.  been  Further,  resolved  as  the  t o the c o o l question  F i r s t , t h e r e a r e only two N s t a r s f o r measured no  N  star  by  the is a  method known  of  lunar  member of an  e c l i p s i n g b i n a r y system so t h a t the r a d i u s may not be by t h i s method.  of  determined  I t i s not p o s s i b l e t o use the c a l i b r a t i o n based  on v a r i o u s photometric  colours  set  up  for M  giants  as the  90  sources  of  giants.  In f a c t the l a t e type carbon s t a r s r a d i a t e more  like  black  opacity  bodies  than  B e s s e l l and Youngbom  S c a l o (1976) blackbody  are- q u i t e  do  M  d i f f e r e n t f o r the carbon and H nearly  s t a r s (Bahng 1966 ; Barnes  1973;  1972).  'has- i n v e s t i g a t e d  temperatures  for  the  carbon  consistency  stars  of  as opposed  temperatures d e r i v e d frcm an M s t a r c a l i b r a t i o n .  using  t o using  He has  derived  blackbody c o l o u r temperatures frcm the' (R-I) , {(R+I)- (J+K)) , K), and from  ( i n most cases) the (I-L) c o l o u r s f o r twenty-three  the  1972a).  available  photometry(Mendoza  1967;  Lee 1970;  He f i n d s the t y p i c a l t o t a l spread i n d e r i v e d  temperature  is  only  50-200°K.  The  (I-  stars Eggen  blackbody  requirement  that  the  blackbody temperatures  be c o n s i s t e n t i s a necessary  requirement  for  effective  it  their  sufficient. from  only  use -as Thus i t - i s  temperatures  but  p o s s i b l e t o get a blackbody  one'colour'measurement,  say  not  temperature  (R-I), and be reasonably  sure that the other c o l o u r i n d i c e s would not g i v e different  is  significantly  results.  B a r t h o l d i e t a l . (1972) have measured an o c c u l t a t i o n angular diameter  f o r the N s t a r , X C n c .  Using Mendoza's(1967)  relation  between Te and-bolometric c o r r e c t i o n t o e l i m i n a t e the b o l o m e t r i c c o r r e c t i o n , they f i n d a Te of about 2500°K. (I-L)'  temperatures  are  probably  too  b o l o m e t r i c c o r r e c t i o n d e r i v e d from the of  However,  small.  aendoza's  I f one uses the  (V-R) c o l o u r index  a  Te  about 26400K i s obtained f o r a f u l l y darkened disk or 2810QK  f o r a uniformly i l l u m i n a t e d one.  Various authors have  measured  91  occultation 1974)  and  diameters  after  The  by  filled  of  M  giants  the c a l i b r a t i o n  crosses  represent  Mendoza(1967).  while  The  of the solid  open  supergiants calibration line  a  circles  by  of  are  The open  Lee(1970) late  r e p r e s e n t s the blackbody  two  f o r which  a n g u l a r d i a m e t e r s have been  than to  t h e two  carbon  t o the H g i a n t use  blackbody  stars  fall  closer  squares the  Miras  are the approximate  how  the  and  type  triangles  Note  function o f G and M  while the f i l l e d carbon s t a r s  for  values.  g i v e n by Lee (1970).  &  Vegt  27QO±100°K  are the c a l i b r a t i o n the  De  Scalo(1976)  of c o l o u r temperature as circles  J o h n s o n (1966)  calibration are  e t a i 1973;  f o r 19 Psc and  a l l the derived  8 shows a p l o t  (R-I).  giants  Psc(Lasker  o f 3050±2000K  considering  Figure of  19  a n a l y s e d them f o r e f f e c t i v e t e m p e r a t u r e s .  adopts a temperature X Cnc  for  relation  positions  of  the  measured.  to the b l a c k b o d y  calibration.  T h e r e f o r e i t seems  temperatures  derived  from  the  by  line  reasonable (R-I)  colour  index.  In  order to help understand  stellar  evolution  theoretical stars  H-R  f o r which  effective  The  was  diagram.  that  to the  is  has  used  9 i s such  to  star's place  place them  a diagram.  been o b t a i n e d a r e  were t h o s e d e r i v e d  (R~I) c o l o u r  o f O l s o n and  carbon  convenient  Figure  photometry  temperatures  curve f i t t e d used  i t  the  and  a  forty  plotted.  The  from a  blackbody  while the b o l o m e t r i c c o r r e c t i o n  R i c h e r (1975) f r o m  Scalo,Despain  in  The  (V-R)  photometry  t h e o r e t i c a l e v o l u t i o n a r y t r a c k s shown have been a d o p t e d  S c a l e (1976)  in  and  U l r i c h ( 1 9 7 5 ) and  from  references  F i g u r e 8.  Colour  temperature  versus  R-  94  cited  therein.  composition, of  All The  these  models  represent  stars  t h i n n e r l i n e s correspond t o the f i r s t  the g i a n t branch t o core helium burning, as  shell  source  models.  ones l y i n g  to  represents  the  the  The  right  model  and  l o c u s o f ' p o i n t s at which the f i r s t helium  shell  of  the  diagram.  shells  mean  The  seven  right  of  this  and are undergoing regular intervals. position  Harm(1965)  for  line  two  The broken l i n e  larger active  thermal pulses i n the  s t a r s ' f r o m ' T a b l e V f o r which-spectra  corresponds  have  the  helium  corresponds  of s u p e r g i a n t s of l u m i n o s i t y c l a s s l a b .  i d e n t i f i e d by a number beside number  The  Paczynski (1970) "and Iben (1972) f o r the  burning  the  double  line  Models to the  to  as  ascent  thick  masses.  s h e l l at f a i r l y  well  disk  double s h e l l source models are the  f l a s h occurs a c c o r d i n g to S c h w a r z s c i l d and 1M©  of  the  were o b t a i n e d are  corresponding  point.  t o the s t a r ' s p o s i t i o n i n Table V.  This  Thus,for  example, 1=1-12, 2=6-6, 7=4-9 e t c .  U l r i c h and the  Scalo(1976)  temperatures  of  the  e s i t i m a t e t h a t the u n c e r t a i n t i e s  in  double  to  possible errors i n convection opacities  i s - no  to  diagram.  source  and  in  adopted  t r a c k s due  the  Scalo(1976)  'temperatures  be about 300°K.  e f f e c t of composition dangerous  theory  more than ±2000R.  the u n c e r t a i n t y i n - the colour  shell  atmospheric  estimates that  from  the  (R-I)  These u n c e r t a i n t i e s , along with the  changes(Scalo  and  Dlrich  make  it  t o ' a s s i g n a mass s o l e l y from the p o s i t i o n i n the  H-R  Therefore the t r a c k s are l a b e l e d mainly  1975)  for  ease  of  r e f e r e n c e although I w i l l be assuming t h a t the s t a r s do have the masses assigned to them.  95  The  f i r s t c o n c l u s i o n to be drawn from Figure 9 i s that a l l  the s t a r s observed appear of'evolution. Eggen(1972b) phase.  T h i s i s i n disagreement that  the  with  the  N s t a r s are i n the core helium  core •surrounded  by  a  phase  suggestion  In the d o u b l e - s h e l l source phase a s t a r  carbon-oxygen still  to be i n the double s h e l l source  ignition  consists  helium burning  f u r t h e r out l i e s the hydrogen burning s h e l l .  of  of  shell  Above  and this  l i e s the outer c o n v e c t i v e envelope  of the s t a r .  stars  c l o s e to the t i p of the 9 M<s>  in  first  this  sample l i e f a i r l y  warmest  g i a n t branch so t h a t i t i s not c l e a r that tnese are  s h e l l source s t a r s as opposed to However f o r the remaining in  The two  a  helium  discussion I w i l l  f a c t double s h e l l source  The  core  double  ignition  assume t h a t  stars. they are  stars.  n e x t " t h i n g to note from t h i s diagram  i s the f a c t  that,  except f o r the f i v e s t a r s -lying t o the l e f t of the 7 all  the  stars*  are  helium s h e l l f l a s h e s * M©  is  bounded -No  on the lower  l e f t by the onset of  c o o l carbon s t a r l e s s massive  massive  than 7 II <g  c o o l carbon s t a r s 'because of the onset of helium s h e l l stars  more-massive than 7 M Q  7  shell  flashes.  These  helium s h e l l f l a s h o b j e c t s as  become flashes.  t h i s f a c t i s u n c e r t a i n as no  models have been c o n s t r u c t e d which are evolved to the helium  than  found i n - t h e pre-helium s h e l l f l a s h phase of e v o l u t i o n .  T h i s s t r o n g l y suggests that s t a r s l e s s  For  track  stars  stage  of  c o u l d very well be post-  well.  The exact mechanism by which the carbon  is  mixed  to  the  96  surface  after  uncertain.  the  Several  suggested ( O l r i c h 1973;  1974;  hydrogen, is  of  the  helium  different  and  Iben  flashes  mechanisms  Despain  1975,1976).  1973;  have  The  basic  that  the  individual  is been  1973; U l r i c h  Sackmann,Smith  carbon and helium i n t o c o n t a c t a t possible  shell  Scalo 1972; S c a l o and U l r i c h  Smith,Sackmann,and  Despain  It  onset  and  idea i s to bring  high  temperatures.  mechanisms  work  more  e f f i c i e n t l y f o r c e r t a i n mass ranges than f o r o t h e r s .  There  exists  relationship Iben  almost  unique  core  Knowing the  shell  source  absolute  star  bolometric  allows  t o c a l c u l a t e the core mass of the most s t a r i n t h i s .sample.  Using Iben's  L/LQ finds  a  core  Chandrasekhar  mass  limiting  of  shell  convective  luminous(bolometrically)  1.73  .  T h i s i s well above the  configuration.  mixing has a l r e a d y occured  Since they are both above the t h e o r e t i c a l  flash envelope  These  stars  mass  The s p e c t r a of s t a r s 1-  2.3MQ ) and  i f they  upper  are pre-  o b j e c t s t h i s i m p l i e s that the "hot-bottom" hypothesis  of  Sealo,Despain,  U l r i c h (1975) may be r e s p o n s i b l e f o r the mixing stars.  It i s interesting  mass { 1.4M<9 ) which i s the maximum  mass l i m i t f o r the core f l a s h ( helium  a  relationship,  and 6-6 i n d i c a t e t h a t s i g n i f i c a n t  i n these s t a r s .  of  = 6x10* (Mcore - 0.41)  f o r such a carbon-oxygen 12  magnitude  one to a s s i g n a mass t o the  c o r e , assuming t h a t the core i s n o n - r o t a t i n g .  one  mass-luminosity  f o r double s h e l l source red g i a n t s (Paczynski 1971;  1976).  double  an  observed  and  i n these  are w e l l above the c r i t c a l l u m i n o s i t y f o r  97  t h i s e f f e c t t o occur.  It i s a l s o worthwhile t o comment star  4 - 9 , number  seven  in  extremely high abundance o f most  1 3  C  on  Fiqure  the  9.  so t h a t  very  interesting  T h i s s t a r e x h i b i t s an  i t is  presumably  the  h i g h l y e v o l v e d o b j e c t i n t h i s sample o f seven s t a r s i n the  sense t h a t s h e l l f l a s h e s have been o c c u r i n g i n t h i s o b j e c t f o r a significant the form  p e r i o d of time.  convective l 3  C  and  respectively.  1 4  As t h e temperature  at the  base  of  envelope i n c r e a s e s i t becomes e a s i e r f o r C t o 1 2  N  by  single  and  I f the temperature  envelope keeps r i s i n g  double  proton  at the base o f the c o n v e c t i v e  i t i s p o s s i b l e that 4-9 c o u l d  way to d e s t r o y i n g i t s carbon s t a r  captures  characteristics.  ba  on i t s  98  VI Summary  In Large  this  to  approximate from  be  by Dr.  Station  several  hemisphere. • i s well  which o t h e r w i s e  a s many a c c u r a t e  carbon  stars  on Mount S t r o m l o .  Photometric  large The  selected  frcm  the  absolute  results to  Mbol - V-R d i a g r a m .  brighter  the  than  observations  were  properties  qroup.  I t i s important to as  possible  of forty  made of  in  carbon  The b u l k  for  carbon  order stars  this  mildly  of  to with  visual  the  bright giant could  observations Two  be  c o l o u r s have been s e a r c h e d f o r  an e m p i r i c a l  However  to  now i s q u i t e s p a r s e .  were f o u n d .  form  t o be  i n the  C o r r e l a t i o n s between a b s o l u t e  photometric  average  the  the d i s t a n c e to t h e Large  magnitudes  the - c a t a l o g u e ,  photometric  i n v e s t i g a t e d ' seem  as  at  Finding charts  o b s e r v a t i o n s on t h e VRI system  no s i g n i f i c a n t  effect  that  known a l l o w s many  m a g n i t u d e and v a r i o u s p h o t o m e t r i c  the  kindly  obtained  telescopes are operatioal fact  known a b s o l u t e m a g n i t u d e s .  but  survey  Such a c a t a l o g u e s h o u l d p r o v e  as t h e data a v a i l a b l e  investigate  prism  p l a t e s he  i s  13.5, t h e  The s t a r s were  would n o t be p o s s i b l e .  obtain  stars,  objective  a e s t e r l u n d from  have been g i v e n .  Magellanic Cloud made  the  i n the  catalogue  t o an I magnitude o f a b o u t  were i d e n t i f i e d .  B.E.  The  stars  c o o r d i n a t e s f o r t h e 309 s t a r s which c o m p r i s e  u s e f u l now t h a t southern  of c o o l carbon  presented.  magnitude o f  Southern  equatorial  catalogue  has been  the- s t a r s  Uppsala  catalogue  complete  limiting  which  identified  and  a  Magellanic Cloud  expected  the  thesis  be  a  branch  on  selection  were r e s t r i c t e d peculiar  stars  stars  to a were  99  found i n t h i s sample of s t a r s . the  catalogue.  They  are  s u b s t a n t i a l amounts of appear  to  1 3  C  These sere s t a r s 1-12 and 6-6 i n  warm  in  luminous  their  stars  which e x h i b i t  atmospheres.  They  also  l i e on t h e Ib s u p e r g i a n t branch i n the Mbol vs (V-R)  diagram.  •'•• • Spectra o f seven members of the catalogue  have  :  obtained  at a d i s p e r s i o n  of 117i/mm.  The spectra  also  been  were obtained  mainly t o c o n f i r m t h a t t h e s t a r s were indeed carbon s t a r s and to a l s o note some o f - t h e found  that-  grosser features  three  of  the  c h a r a c t e r i s t i c s : " a higher defined  than  normal  stars  characteristics.  One s t a r ,  The  spectrum of 4-9 i s the C * N 1 3  bands i n v o l v i n g  1 3  It  exhibit  abundance  J  of  1 3  was star  C,  as  T h i s was unexpected  a much l a r g e r number of s t a r s than f o r  carbon s t a r s i n our Galaxy.  the-  seven  by Bouigue (1954) and Gordon (1967).  as t h i s i s p r o p o r t i o n a l l y  star  i n t h e spectrum.  a  most  4-9,  showed  outstanding  band at  ^6260.  extreme  feature In  J  i n the  many  cases  C are s t r o n g e r than the c o r r e s p o n d i n g  C  iZ  ones.  The well  evolutionary  understood.-  s t a t u s o f carbon s t a r s It  is  useful  to  t h e o r e t i c a l H e r t z s p r u n g - R u s s e l l diagram their  evolutionary  development.  for bolometric -corrections effective were  temperatures  placed  positions  in  a  place  the  to  aid in  stars  blackbody  in a  explaining  temperatures  argued f o r by Scalo(1976)  theoretical  presently  Using the best a v a i l a b l e  and using  as  i s not  H-R  diagram.  of the s t a r s are a b i t u n c e r t a i n  data as  the s t a r s  Although  the  due to the e f f e c t s of  100  composition  changes  and  temperatures,  the cool  carbon  double s h e l l have  two  active  hydrogen. pulses and  source  seem  are  become c a r b o n 1-12  and  solar  masses.  although  constructed star's  bounded  It i s  guite  the  appear  point  by  1975). to  by  that  which  the  a n d one o f thermal  Shwarzschild  be s l i g h t l y  helium shell  mass  peculiar  stars stars,  more m a s s i v e t h a n  ba p r e - h e l i u m s h e l l as models  detailed  solar  helium  intermeriate  The two m i l d l y  i s uncertain are  as d e s c r i b e d  possible  These s t a r s may  a  several program  large  enough  telescopes  of obtaining  many o f t h e s e s t a r s as p o s s i b l e be  possible to devise  temperature,luminosity Higher brighter of  helium  the s t a r s  below by t h e o n s e t o f t h e s e  mechanism  stars(Iben  which  that  hemisphere  may  of  have at  the  flash not  seven  objects  yet  this point  been  i n the  evolution.  Now  as  certainly i n  I n t h i s phase  one  derived  the s t a r s l e s s massive tuan seven  be  6-6,  this  burning s h e l l  In f a c t  to  flashes.  flashes  shells,  the  I t a l s o . a p p e a r s as though they a r e undergoing  Harm (1965).'  shell  burning  in  s t a r s are almost  phase o f e v o l u t i o n .  i n the helium  masses  uncertainties  dispersion objects  medium should  in  the  southern  dispersion spectra of be s t a r t e d .  a classification  Then  spectra  should  be  stars.  i t  s y s t e m i n which t h e  and abundance e f f e c t s c a n be s o r t e d  t o a i d i n unerstanding  the c o o l carbon  exist  obtained  o f some  the evolutionary  out. of the status  101  Bibliography, Bahng,  L. 1966, i n C o l l o q u i u m on L a t e - T y p e S t a r s , e d . Hack ( T r i e s t e : O b s e r v a t o r i o d i T r i e s t e ) , p. 255.  Barnes,  T.G.  1973, Ap.  J.  Suppl.  S e r . No.  M.  221, 25 , 369.  Bartholdi,  P., E v a n s , D.S., M i t c h e l l , H.I., S i l v e r b e r g , E.C., S e l l s , D.C., and H i a n t , J.R. 1972 A . J . , 77 , 7 5 6 .  Bessell,  M.S., and Youngbom, Australia, 2 ,154.  Bok,  B.J.,  Bouigue,  and Bok, P.F.  R.  Gatchpole, De  Vaucouleurs,  De  Vegt,  C.  Dickens,  1975, Pub. G.  1972,  Proc.  Astr.  JP7 , 104.  A.S.P., 87 , 397.  1955, A . J . , 60 , 4 0 .  1974, A s t r . and Ap., 34 , 457.  R.J.  1972, M.N.R.A.S., .159 , 7.P.  Eggen, O . J .  1972a, Ap.  Eggen, 0 . J .  1972b, M.N.R.A.S., J 5 9 ,403.  J . , V74 , 45.  G o r d o n , P.C.  1967, d i s s e r t a t i o n , U n i v e r s i t y o f M i c h i g a n .  G o r d o n , P.C.  1968, P u b .  A.S.P., 80 , 597.  Iben,  I.  1972, Ap.  J . , 128 , 433.  Iben,  I.  1975, Ap.  J . , J 9 6 , 525.  Iben,  I.  1976, Ap.  J . , t o be p u b l i s h e d .  J o h n s o n , H.L.  1966, Ann. - Rev.  "  Astr.  and Ap., 4 , 193.  Keenan, P . C , and Morgan, H.W.  1941, Ap.  Lasker,  and  Lee,  B.M., Bracker, S.B., A.5.P., 85 , 109. •  T.A.  Mavridis,  Soc.  1962, M.N.R.A.S., J.24 , 435.  1954, Ann. d * Ap., R.M.  L.  1970, Ap.  J . , 94 , 501 .  Kunkel,  W.E.  1973, Pub.  J . , J 6 2 ,217.  L.N. 1967, i n C o l l o g u i u m on L a t e - T y p e S t a r s , e d . Hack ( T r i e s t e : O b s e r v a t o r i o d i T r i e s t e ) , p . 4 2 0 .  Mendoza, E.E. 305.  1967, B u l l .  Tonantzintla  Mendoza, E.E.,  and J o h n s o n , H.L.  y Tacubaya  1965, Ap.  Obs.,  J . , 141 , 161.  3  M. ,  102  Olsen,  B . I . , ana R i c h e r ,  Paczynski,  B.  H.B.  1970, A c t a  1975, Ap.  J . , 200 , 88.  A s t r . , 20 , 47.  Richer,  H.B.  1971, Ap.  J . , J.67 , 521.  Richer,  H.B.  1972, Ap.  J . ( L e t t e r s ) , 172  Richer,  H.B.  1975, Ap.  J . , 197  , L63. i  Sackmann,  , 611.  I . J . , S m i t h , R.L., and D e s p a i n ,  187 , 555.  Scalo,  J.M.  1973, Ap.  J . , J 8 6 , 967.  Scalo,  J.M.  1976, Ap.  J . , 206 , 474.  Scalo,  J.M., D e s p a i n , , 805. >  Scalc,J.M.,  Shane, C D .  1974, Ap.  J.,  1  K.H.,  and U l r i c h ,  Schwarzschild,  K.H.  and U l r i c h ,  R.K.  R.K.  1975, Ap.  M. , and Harm, R.  1928, L i c k Obs.  1975, Ap.  J . , 196  J . , 200 , 682.  1965, Ap.  J . , 145 ,496.  B u l l . , "1.3 , 123.  Smart, W.M. 1971, T e x t b o o k on Spherical Astronomy(5th Cambridge:Cambridge University Press),p. 278.  ed.;  :  Smith,  R.L. Sackmann, I . J . , and Despain, K. H. , 1973, i n E x p l o s i v e N u c l e o s y n t h e s i s , e d . D.N. Schramm and W.D. A r n e t t ( A u s t i n : U n i v e r s i t y o f T e x a s P r e s s ) , p. 168.  Ulrich,  R.K. 1973, i n E x p l o s i v e Nuleosynthesis, ed. D.N. Schramm and M.D. A r n e t t ( A u s t i n : U n i v e r s i t y of Texas P r e s s ) , p. 139.  Ulrich, L37.  R.K.,  and S c a l o ,  J.M.  1972,  Ulrich,  R.K.,  and S c a l o ,  J.M.  1976, i n p r e p a r a t i o n .  Hallerstein,  G.  1973, Ann.  Rev.  Ap.  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