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¹²CO observations of the molecular cloud encompassing Sharpless 222 (LK Hα101) Christie, Richard Allan 1981

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1 2  CO  OBSERVATIONS OF THE MOLECULAR  CLOUD ENCOMPASSING SHARPLESS 222 (LK HOflOl) by RICHARD ALLAN .Sc.,  The U n i v e r s i t y  CHRISTIE  of B r i t i s h  Columbia,  197  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE  REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in  THE  FACULTY OF GRADUATE  STUDIES  DEPARTMENT OF PHYSICS  We a c c e p t to  THE  this thesis  the required  standard  UNIVERSITY OF BRITISH COLUMBIA August  ©  as comforming  Richard Allan  1981  C h r i s t i e , .1981  In p r e s e n t i n g requirements  this thesis f o r an  of  British  it  freely available  agree for  that  understood for  Library  shall  for reference  and  study.  I  for extensive  that  his  or  be  her  copying or  f i n a n c i a l gain  shall  P H VS  publication  not  be  DE-6  (2/79)  the  of  Columbia  make  further this  thesis  head o f  this  my  It is thesis  a l l o w e d w i t h o u t my  IC S  The U n i v e r s i t y o f B r i t i s h 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  by  representatives.  permission.  Department of  copying of  granted  the  University  the  p u r p o s e s may by  the  I agree that  permission  department or  f u l f i l m e n t of  advanced degree at  Columbia,  scholarly  in partial  written  ii  ABSTRACT The of  4.57  meter m i l l i m e t r e wave t e l e s c o p e a t  British  around  Lk  Columbia Hiy.101  has  one  half  #(1950) = 04 26 34^0 H  i n the  Our  results  the  12  CO  exact  as  far  region  as  a  almost  field  found  13  generated  are  as  yet  of  We  temperature,  1 2  C 12  1 6  the  35°13'00"  emission,  but  n o r t h and  emission  west  extends  1 magnitude which c o v e r s degrees  , i s 10 R.  fragmented  on  0.  CO  several  T*  a region  6(1950) =  suspect of  map  centered  u n d e t e r m i n e d . The  extinction  a large  CO  envelope Three  clouds Lk  masses  densities clouds  and  (#4  H0<101  12  CO  area  with  have  are and  HO(101  from  upon v e r y  made  #2,  and  long.  a  The  Within  our  survey  five  hot  spots  are  (0.0,-10.8),  and  #5)  limit  on  the  Lk  Hon01  these  centered  25M  on  Lk  of  13  CO  CO  and  within  a  single  Lk  H«1 0 1 .  of  was 13  CO  (7.2,-5.4). 13  CO  column  respectively.  Two  resolution  l o c a t e d at  fragments  fabricated  12  generated  (0.0,-1.8) and  HC*101  data  LkHoqOl  the @  CO  r e s o l v e d a t Lk HC<101  and  from  13  southeast  #3)  calculated  the  spots  located  0  the  not  hot  49M , 41M©,  0  contour  five  emission  (#1,  were  were  o b s e r v a t i o n s . Both  2 5 M . E a c h of  calculated relied  CO  (3.6,-5.4) and  and  0  12  contours  (7.2,-10.8),  13 K  the  o f c o l d e r CO  CO  Their  observations  from  temperature  11M  diameter  University  K). Since  Lk  transition  d e g r e e a c r o s s and  radiation  we  in  show a wide r e g i o n of  visual one  to p a r t i a l l y  ascension),  have been d e t e r m i n e d .  average  (20  J=1—0  boundaries  boundaries  used  degree  (right  M  (declination)  been  the  are  have  i s embedded  (3.6,-7.2). data  strongly. It i s in error  by  and  other  masses i n the  The  same  mass  should  a t most a  of  not  factor  is be of  iii  two. Peak HI  emission contours  anticorrelated northwest. in  derived  from  From  both  CO  the  The  10  has  the  northwest  and  Roger  The 13  CO  made  The  and  peak  HI  HI  HI  d a t a and  1981) lies  are  to  features  column HI  the are  densities  observations  cm . - 2  of t h e  with  r e g i o n we  r e g i o n s of  o c c u r s where t h e  see  that  stronger  extinction  where t h e v i s u a l this  extinction asymmetry  i s a steep d i s c o n t i n u i t y  i s low. into  i s lower.  The HI  Dewdney  reasonably well  of d e n s i t y n e a r  the  visual  p r e s u m a b l y been a b l e t o d i s s o c i a t e H^  (1981) have m o d e l l e d there  Roger  contours.  atoms  2 1  we  peak HI  to  by  Lk HCV101  east.  The  positions  Observatory  Near  evidence  f o r the  suggest  that  c l o u d and  H0(101  map  infrared  'Blister'  star  generation  of  Infrared  proceeded  more c o m p l e t e Lk  x  and  t h e peak CO  emission c o r r e l a t e s  star  next  that  fabricated  counts  exciting  t o the  CO  regions.  ~1.3  star  extinction.  assuming  peak  different  They a r e  stronger  our  This indicates  located  agree.  to  (Dewdney  of  (3.6,-7.2).  Photographic model  formation inwards. infrared  with  stars  better  Our  Sky  (Israel was CO  stars.  from Survey  1977,  initiated hot  the  p r o v i d e meager  Gilmore on  1978)  t h e edge of  spots could well  Confirmation w i l l  resolution  Steward  of  the  be  and the the  require a  region  around  iv  TABLE OF  CONTENTS  Abstract  .n  T a b l e Of  Contents  List  Of  Figures  List  Of  Tables  i  V vi  Acknowledgements I.  Vii  INTRODUCTION  II.  1  DATA ACQUISITION  6  I I . 1-Site  6  11.2- E q u i p m e n t  7  11.3- O b s e r v i n g 11.4- O n - S i t e III.  Sequence  Data  10  Handling  DATA REDUCTION AND  19  ANALYSIS  21  III.1-Calibration  21  I I I . 2-Representation III.3- CO 1 2  Of  Lk HW01  Through G l o b a l P l o t s  R a d i a t i o n Temperatures  III . 4-Generating 111.5- G e n e r a t e d  Model For 13  CO  111.6- S t a r C o u n t i n g IV. DISCUSSION OF  —  31 36  CO  41  Column D e n s i t i e s  48  Theory,  13  Data  And  Results  RESULTS  55 71  IV.1.1-Previous  Observations:  Introduction  IV.1.2-Previous  O b s e r v a t i o n s : HI  Results  78  IV.1.3-Previous  O b s e r v a t i o n s : CO  Results  83  IV.2-Our O b s e r v a t i o n s V.  y  71  86  CONCLUSIONS  103  Bibliography  105  A p p e n d i x : T*  (  1 2  C O ) Contours  At C o n s t a n t  Velocity  108  V  L I S T OF FIGURES  Figure  1-The R e c e i v e r  Figure  2-Reference P o s i t i o n Spectrum  Figure  3-Lk HOC101  ( 5 . 4 ,-3 . 6 ) - T i p p i n g  Figure  4-Lk H C X 1 0 1  (5.4,-3.6)-OMC1(Or i o n A) C a l i b r a t i o n .... 30  Figure  5-Global Plot  ( T i p p i n g Curve C a l i b r a t i o n )  33  Figure  6-Global Plot  (OMC1(Orion  35  Figure  7-Integrated  CO Contours  Figure  8-T* (  Figure  9-Generated  Figure  10-Generated N  Figure  11-A  B  E x t i n c t i o n Contours  63  Figure  12-A  H  E x t i n c t i o n Contours  64  Figure  13-A  v  E x t i n c t i o n Contours  65  Figure  1 4 - I n f r a r e d Diagram  Figure  15-HI C o n t o u r Map, F e l l i  Figure  16-HI P r o f i l e ,  Dewdney And Roger  Figure  17-3-D D i s p l a y  Of HI R e s u l t s  Figure  18-  Figure  1 9-Comparison  1 2  1 3  1 2  9 18  C O L  C0 Profile  (  1 3  47  C O ) Contours  54  77 And C h u r c h w e l l (1972) (1981)  1 2  C O , HI, A  80 81 82  Dip Of  45  CO) Ratios  CO) Contours  1 3  28  40  1 2  1 3  Calibration — .  A) C a l i b r a t i o n )  C O ) V s . T* ( C O ) / T * ( T* (  Curve  85 v  Etc  NOTE: SIX OVERLAYS OF THE RESULTS FOR FIGURE 19  102 . . . . i n pocket  vi  L I S T OF TABLES  Table  I-Observation  Table  II-T*  Table  Ill-Profile  Half  Table  IV-Velocity  Calculations  T a b l e V-Van  (  1 3  Details  CO) Generating  14 Model  44  Width R a t i o s  51  Rhijn's Table  52  For b = -9.0°  T a b l e V I - D a t a Summary  67  Table V l l - I n f r a r e d  Star  Table VHI-Peak  N  (  Table  IX-Virial  Cloud  Table  X-N  f n L  (  1 3  CO)  C O L  1 3  61  Positions  C O ) And R e l a t e d h Masses  C l o u d Masses  75 v  98 99 100  vi i  ACKNOWLEDGEMENTS I for  wish  t o thank my t h e s i s  h i s continued  course  of t h i s  I and  Drs.  suggestions  during  the  I would l i k e  Shuter  valued c o n t r i b u t i o n s . to  thank  of unpublished  three data  groups  for  on S h a r p l e s s  their  regions:  P. Dewdney and R. Roger a t t h e D o m i n i o n R a d i o A s t r o p h y s i c a l (D.R.A.O.), f o r t h e i r  E. Craine  Sharpless of  fortheir  contribution  Observatory Dr.  and  t h e o t h e r members o f our g r o u p , D r . W.L.H.  Mr. C P . Chan  generous  encouragement  McCutcheon,  project.  thank  Finally,  s u p e r v i s o r , D r . W.H.  of the Steward O b s e r v a t o r y ,  222 from  the U n i v e r s i t y  second three  year  Sharpless  their  of Maryland  project  Sharpless  infrared  covering  regions.  1 2  C0  and  HI  f o r sending  sky survey  f o r sending  222  a p r i n t of  a n d D r . P.  a" c o p y o f 1 3  results,  Jackson  J . Sewall's  C 0 observations for  1  I. The  J=1—*0 t r a n s i t i o n  detected that  by  Wilson  CO column  regions.  It  emission  from  indicators The  was  recognized radio  could  through  thick  be  found  in  transition  a  and maser  0  was  well  that  first  e t a l . (1971) higher  emission,  line  found  near  HII  along  with  emission, are often  once.  CO  is  the  most  and i t s r e l a t i v e l y even  molecular abundant  long  in  lifetime  regions  with  P e n z i a s e t a l . (1972) showed t h a t  populated  in  typical  between  CO and n e u t r a l  if  J=1—>0  the  dense  hydrogen  transition  cloud,  by t h e  molecular  clouds  molecules.  was  optically  thermalization  radiative  this  trapping  of  the  of  the  photons.  saturated  the  found  to determine  CO  rates.  w o u l d be a s s u r e d  h a s been  1 3  CO  c a n be p o p u l a t e d  uniformly  Wherever  CO  that  molecule,  collisions  They a l s o  1 3  Penzias  1 6  formation.  at  t h e J=1 l e v e l  excitation  J=1—>-0  C  1 2  systematically  accepted  of r e c e n t s t a r  means t h a t  it  now  are  other molecules  interstellar  level  interstellar  e t a l . (1970).  desities is  of  u s e o f CO e m i s s i o n a s a p r o b e o f i n t e r s t e l l a r  clouds  small  INTRODUCTION  the  J=1—*0 t r a n s i t i o n  t o be o p t i c a l l y kinetic  probing The  thick  depth  1 3  abundant  (Sewall  t o use t h e even  less  has been  and hence CO  than  as a d e n s i t y probe.  has a h i g h o p t i c a l  would be b e t t e r  1 2  temperature.  since i t i s far less  i s g e n e r a l l y used  f o r CO  1 2  i t c a n be u s e d  is  not  usually  CO.  As a  result,  In  some  cases  1980). F o r t h i s  abundant  detected  1 2  C  1 8  0  even  reason i t  isotope for  dense c l o u d c e n t r e s . cause  considerable  of  the  observed  controversy.  The  CO  line  thermal  widths line  has  width,  sparked assuming  2  typical  parameters  Observations these  line  f o r a molecular  indicate  widths  velocities.  line  would  widths  energy  damping. G o l d r e i c h and Kwan  profiles  of  appearances  cloud,  they  systematic Kwan than  motion  they  release  that  that  the  be  that  heated  by  energy.  implied  by c o l l i s i o n s  rapid  the l i n e  widths  are  Since the  generally  variations  throughout the  undergoing  some  by  CO  compression  F o r v e r y warm c l o u d s line  emission  (T £- 25 K) K  intensities  between t h e gas m o l e c u l e s  and t h e  could  by b u r i e d p r o t o s t a r s .  The f r e q u e n t a s s o c i a t i o n  CO  with  point  favor for  of t h i s most  CO  strong infrared  m o d e l . The l a r g e line  shapes,  velocity  will  IV.3. one as  one  g r a d i e n t model  description  of  needs t o i n c o r p o r a t e c o m p l i c a t e d h y d r o d y n a m i c t u r b u l e n c e , clumping,  and e d d i e s  CO and Hoc v e l o c i t i e s  generally  CO v e l o c i t y .  finds  near  t h e Hex v e l o c i t y  This suggests  accounts  by Zuckerman and Palmer  o f t h e s e a r g u m e n t s more f u l l y  To o b t a i n a more d e t a i l e d  When one  discuss  that  of  i s evidence i n  b u t t h e r e a r e some s t r o n g  a r g u m e n t s . T h e s e a r e summarized We  sources  be  and t h e d u s t  grains heated emission  have  c o l l a p s e . G o l d r e i c h and  adiabatic  by t h e CO  motions,  prevent  species  clouds  dispersion  motions.  the clouds c o o l e d f a s t e r  of g r a v i t a t i o n a l  maintained  isotopic  1  larger. Generally,  to  turbulent,  such as g r a v i t a t i o n a l  could  the temperatures  than  km s ~ .  by t u r b u l e n t  required  a n d show a n a l o g o u s  argued  (1974) f o u n d  are  0.1  supersonic  a r e caused  different  similar  to  (1974) p r o p o s e d  a r e due t o s y s t e m a t i c , r a t h e r line  many t i m e s  correspond  I f the l i n e  tremendous s o u r c e s o f  widths  c l o u d , i s about  star  opposing (1974).  in section formation  processes  such  i n c l o u d models. an HII r e g i o n a r e a v a i l a b l e t o be more n e g a t i v e t h a n t h e  ionized  material  is  streaming  3  away  from  emission. (Israel just  neutral  1977,  they  formation  Gilmore  led  1978). In  this  surfaces  give  process  are  triggering  rise  passage  of  perhaps  recently model  by  generations  generated  are  1979)  to  the  model OB  one  near  HII  the  the  neutral  formed  by  the  ( E l m e g r e e n and gives  the  shock Lada  similar  Compact  i s b e l i e v e d t o be  spiral  formation density  waves  1977). The  results  using  star  complex  clouds.  Star  form  clouds  cloud  of  CO  model  r e g i o n s . The  cloud.  clouds. and/or  the  'Blister'  edge  star formation  to  molecular  s i d e of  into  rise  associations  elongated  supernovae  stars  (Tenorio-Tagle  on  found  the  gives  ultracompact  proceeds  for  into  initiated  Subsequent  huge  to  generally  shocks  of  is initiated  mechanism  which  have  autocatalytically  regions  material  Such o b s e r v a t i o n s  i n s i d e the  where  and  the  HII The the is  waves.  from  the  Champagne numerical  modeling. Habing sequence  and  Israel  f o r compact  HII  (1979) g i v e  the  following  evolutionary  regions.  "1. The y o u n g e s t o b j e c t s a r e i n f r a r e d s o u r c e s without any HII r e g i o n s , a s s o c i a t e d , i f a t a l l , o n l y w i t h HgO masers h a v i n g simple l i n e p r o f i l e s . These objects may be identified with a c c r e t i n g s t a r s . ... 2. S l i g h t l y o l d e r a r e t h o s e o b j e c t s w h i c h a r e s i m i l a r , but w h i c h i n a d d i t i o n show h i g h v e l o c i t y peaks i n t h e H 0 maser l i n e profiles; these peaks i n d i c a t e t h e e x i s t e n c e of a s i g n i f i c a n t s t e l l a r wind, i m p l y i n g t h e end of t h e a c c r e t i o n p h a s e . ... a  3. Next a r e the infrared sources associated with the smallest HII regions (3X10 cm d i a m e t e r ) . ... A p p a r e n t l y the HII r e g i o n has grown s u f f i c i e n t l y i n size to become visible. Surrounding the HII region is a dense s h e l l t h a t sometimes h o u s e s an OH maser s o u r c e . 1 6  4. When t h e HII r e g i o n has expanded b e y o n d a diameter of 3X10 cm, t h e OH maser d i s a p p e a r s and a b l i s t e r - t y p e HII r e g i o n w i l l soon a p p e a r . " 1 7  4  Why  map  previous be  C0  1 2  emission  work, summarized  in  Sharpless  i n s e c t i o n I V . 1 , show S h a r p l e s s  a young, compact HII r e g i o n w i t h  ongoing mapped  star  formation.  this  resolution decided  Recently  i n the  map  would  approximately  line  The the  HI  meaningful.  arcminutes  reasonable  shown  the  of  anticipated.  the approximate  in  a poor  extent  HI  be  was a c t u a l l y  As a r e s u l t  mapped  cloud  of t h i s  is  and  First,  observations,  so t h a t we have d e t e r m i n e d  the  edge.  particularly interesting clouds  to  field.  to  we c o u l d o n l y  source  a  the  the  for have  resolution.  size  indicated  This  observations  beam  by t h e  width  In r e t r o s p e c t , t h e observations greater  than  consuming had the  only  to  Sharpless  222  we had  a of  60 p e r c e n t  partially  have  technical  make  extent  of  few our  of the  sample much o f has  been  a  t o e x a m i n e . I t has y i e l d e d many molecular  formation.  purpose of t h i s  describe  region  also  phenomena and a p p e a r s t o be p r o t o t y p i c o f in star  222.  time.  we  limit  Nevertheless,  profitable  engaged  For used  Secondly,  observation  telescope, had  of  we  a  time  compromises.  we  Sharpless  CO  far  with  work  and  Our  difficulties  cloud's  the  their  angular  with  assumption.  the  an  have  possibilities  and v e l o c i t y  could  latter  with  observations  between t h e  a  (1981)  constituents  CO  spatial  As w e l l ,  HI c o n t o u r  emission  additional  and  same  and Roger  c l o u d encompassing  provide  would make any c o m p a r i s o n  several  Dewdney  222 t o  s t r o n g p o s s i b i l i t y of  In c o n j u n c t i o n w i t h  the molecular  interpretation.  outermost  a very  HI a n d CO sample d i f f e r e n t  this  more  HI  of 2 arcminutes.  to  Generally and  region  222? The r e s u l t s o f  p r o j e c t t h e name S h a r p l e s s  molecular  cloud  encompassing  222 i s  the  HII  5  region,  NGC  1579,  while L k HC<101 denotes  of the i l l u m i n a t i o n . The l a b e l p l o t s and  tables.  the a s s o c i a t e d  one exception i s the use  of  source  LH101  to  6  I I . DATA ACQUISITION II.1-Site Observations using  t h e 4.57 meter  University McCutcheon  of  elevation CO  t h e S h a r p l e s s 222 r e g i o n millimetre  British  1974, Mahoney  123°13'56"  1 2  of  West i s about  frequency  campus  1976). The  50 m e t e r s  of  wave t e l e s c o p e  Columbia  longitude,  telescope  49°15'11"  is  degrees which map  ±0.015  s p a c i n g . The beam e f f i c i e n c y  latitude.  has an  i s about  at  at The the  effective of  i s a t worst  power beam s p a c i n g  the  situated  repeatability  tracking  on  ( S h u t e r and  Operating  the t e l e s c o p e  degrees. Source  amounts t o t h e h a l f  is  North  above sea l e v e l .  115.271 GHz,  located  i n Vancouver  beam w i d t h o f 0.044 d e g r e e s . The p o i n t i n g telescope  were c a r r i e d o u t  the ±0.03  used a s o u r  37 p e r c e n t .  7  II.2-Equipment The arsenide  receiver  uses a  Schottky  single  barrier  ended  mixer  d i o d e . Both  two s t a g e p a r a m e t r i c a m p l i f i e r  with  the s i g n a l  a r e kept c o o l e d  to  a  gallium  mixer 20  and t h e K  in  refrigerated  dewar a t t h e f o c u s o f t h e t e l e s c o p e . A t 115.271  the  noise  system  temperature  1200 K  (SSB). A schematic  Figure  1.  Spectra  were  spectrometer. frequencies  range  Spectra various  Each  channel  from  forms  Full  section II.4.  The o n - s i t e details  receiver  using is  299.500 MHz  of r e d u c t i o n  GHz  f o r these o b s e r v a t i o n s averaged  the  obtained  were a c c u m u l a t e d  minicomputer. (1976).  of  a  250  used  a KHz  64  is  channel  wide.  t o 315.250  programs  be c a r r i e d were  of the o n - s i t e  The  in  filter channel  MHz.  in a Fabri-Tek signal could  given  a v e r a g e r and  o u t by a NOVA  developed  by  1200  Mahoney  data handling are given i n  8  Figure  1 -The  Figure receiver  at  Receiver  1 i s a schematic diagram the  University  system  temperature, T  normal  operating  $ Y S  of  , i s about  conditions.  of t h e 80  British 900  K  t o 120  Columbia.  (single  GHz The  cooled average  sideband)  under  ANTENNA | HUT I  CMARr RicOHSER  PIS  IF. M F , SYNCHRONIZER  P.5.  REF.  IF.  5*SE  C80025 RAPK3  ASmtWOMY  IO/4/T9  80-120 GHZ. C O O L E D  R E C E I V E R  10  II.3-Qbservinq  Sequence  Eighty-nine region, fill  at  Lk  spacings  a circle Often  HCX101  p o s i t i o n s were o b s e r v e d  one-half  a  the  0.03  arcminutes with  in  where  respect  (Right  M  Dewdney star  and  Lk  Roger  spectra  (1981) HI  s c a n s and  OFF  source,  receiver  Lk  obtaining  a  position  for  spectrum 320  scans  i s to  noise  and  region  is required  by  As  by  to obtain  written  and  Lk  The  approximate centre a  scan  in  purpose  region  scans  and  in  the  a  single  of  obtaining  reference  subtract  receiver  to  s e l e c t i o n of f r e e of  CO  fixed  the  course  collected  almost  s c a n s of  the  of  of  a  the  this  emission.  reference  project region.  beam  reference  6 ( 1 950) =34 °1 0' 00 '.'0  p o s i t i o n . In  load  process  «(1 950) =04 26*51 . 7 , &  the  source,  Palomar p h o t o g r a p h i c  reference  of  the i l l u m i n a t i n g  r e f e r s to  on  stability  a  result,  the  thirty  HO(101  Ascension)  reference  term  i n s p e c t i o n of H  as  declination  a l t e r n a t i n g between ON  or  seconds.  be  (5.4,-3.6).  contributions. Careful  meticulous v i s u a l selected  the  integrating  improve b a s e l i n e sky  as  H0OO1  R,  mode. The  would  (Declination)  map.  were o b t a i n e d  switched  we  chosen  HCX101 i s l o c a t e d a t  The S,  p o s i t i o n was  222  nominal c e n t r e p o s i t i o n ;  6 ( 1950)=35°13'00':0  centre  observed  following  ascension  (X{ 1 9 5 0 ) = 0 4 2 6 3 4 t o  This  will  numbers  right  H  region  position  the  t o our  Sharpless  diameter.  spectral  o f f s e t s in  the  d e g r e e s . The  degree  specific  (x.x,y.y)  represent  of  in  After prints as  we  our have  Summation  11  of  these  scans  i n d i c a t e s there  reference  region. Generally  spectrum  is  added  to  i s negligible  the  1 2  C0  signal  i n our case  s i n c e t h e maximum T  was  much  than  average p r o f i l e spectrum In  order  necessary  (  A  1 2  C0)  neglected.  require  third  telescope half  that  four  the t o t a l  format.  The  a  better  his  efficiency  recommendations, a  3  different  Beam  we o b s e r v e d (1980)  S, ,  ratio  period  pairs.  method  a  is  the  M  time  s  of i n t e g r a t i o n time. is  spent  moving t h e  remaining  S ,  and  3  have  time, decided  S  the t o t a l  Szabo  followed  observing  sequence  a l l represent  4  four  times  integration  time  t h e same r e f e r e n c e  o f any c o r r e l a t e d  were kept f a r  noise.  The  one  s e q u e n c e and Szabo's. (1980) was p o s i t i o n s each n i g h t  p o s i t i o n s each  technically  represent  e a c h map p o s i t i o n  s e q u e n c e was r e p e a t e d  sixteen different  four d i f f e r e n t  used  We w i l l  that  21 2 0  the  to give  the e f f e c t  we  mapping had t o be f o u n d .  S ,  between o u r o b s e r v i n g  he o b s e r v e d  of t h e  reference  p o s i t i o n . I t was t h e n  using  p o s i t i o n s using  to minimize  difference that  averaged  i n h i s t h e s i s . We  positions. This  the observing  desired. apart  Here  H  map  for  t h i s problem  //S,R S / S R S / / .  during  observing  on t h e r e f e r e n c e  (1980) c o n s i d e r e d  reference  amount o f i n t e g r a t i o n t i m e  minus OFF s o u r c e  our  the  (rms) n o i s e  from one p o s i t i o n t o a n o t h e r . Of t h e i s spent  reference  E a c h s p e c t r u m was t h e sum o f f o u r  scans which t o t a l  of  the  2.  to determine  ON s o u r c e  s i g n a l i n the  in  mean s q u a r e  a s f o l l o w s /SR/SR/SR/SR/. We d e c i d e d  One  one  root  in Figure  observing  consecutive  would  in  to give a s u i t a b l e s i g n a l to noise  following  this  the  and c a n be  i s given  C0  e a c h o f t h e map p o s i t i o n s . T h i s was n o t  done  less  1 2  better  four  times.  whereas Szabo's  s i n c e he s p r e a d s t h e d a t a  12  for  these p o s i t i o n s  calibration  of these  noticeable our  over  improvement  sequence  since  four same  nights  and uses  evenings.  However,  u s i n g h i s method, and  i t allows d a i l y  t h e averaged  on-site  we  found  therefore,  no  we c h o s e  a v e r a g i n g of the  four  spectra. Each  day  calibration  sources  calibration. observing  session  variations  t o check  t o check  i n opacity.  was o r i g i n a l l y  Lk HCX101. As t h e p r o j e c t  that  more  widespread  we c o u l d  cloud. region  around  where t h e  Table sequences  map  over  a  12  our r e l a t i v e end  the  i s given  half  hour  for the  temperature.  map t h e  and  entire  region  as well  around  found  to  i t was d e c i d e d field  in section  sampled  each  t o check  C0 e m i s s i o n was  sample  of  the atmospheric  known sky  anticipated  as  of  the  III.2. A small  as a  wide e x t e n t o f t h e c l o u d  c r o s s and  to  determine  C0 e m i s s i o n d e c r e a s e s . I  summarizes  used  indication antenna  proceeded,  of  every  intended t o f u l l y  Lk HCX101 i s f u l l y  strips 12  u s i n g the  no l o n g e r f u l l y  of  was m o n i t o r e d  Approximately  t h a n we had  The r e s u l t i n g  diagonal  the c o n s i s t e n c y  was c a l i b r a t e d  0MC1(Orion A)  a t t h e b e g i n n i n g and  The s k y t e m p e r a t u r e  spectrometer  be  (5.4,-3.6) and the accuracy  OMC1 was o b s e r v e d  attenuation.  It  we mapped Lk HK101  of  t o obtain  positions  the spectra.  t h e atmospheric  tipping  temperature.  the dates,  measurements  Also  attenuation and  the  and o b s e r v i n g included  determined receiver  i s an from system  1 3  Table  I -Observation Table  t h e y were opacity ( f  I  gives a l i s t  observed. at  the  i n nepers)  centre  Details  Also  of the s p e c t r a l  points  given  average  beginning  and  the  is  and  system  the  end o f e a c h temperature,  and t h e d a t e s  observing T  S Y S  (0.0,0.0) p o s i t i o n i s ,  (X ( 1 950 ) = 0 4 2 6 3 4 ^ 0 H  M  8(1950) = 35°13'00V0  (Right  atmospheric  Ascension)  (Declination)  session,  (SSB).  The  Table Date day/month  I -Observation  Points  t start  Details  - end  (SSB)  29/4  (+5.4,-7.2) (+5.4,+3.6) (+5.4,-5.4) (+5.4,+7.2)  0.319- 0 .373  1358  30/4  (10.8,-3.6) (+3.6,-3.6) (-3.6,-3.6) (-9.0,-3.6)  0.377- 0 .375  1222  0.460- 0 .456  1134  (+0.0,-3.6) 1/5  (-9.0,+5.4) (-9.0,-1.8)  1&2/5  (-9.0,10.8) (-9.0,-10.8)  2/5  (10.8.+0.0) (-1.8,+0.0) (+5.4,+0.0) (-9.0,+0.0)  0.327- 0 .311  1186  3/5  (0.0,-10.8) (+0.0,+0.0) (+0.0,+5.4) (0.0,+10.8)  0.351- 0 .273  1134  4/5  (-5.4,-10.8) (-5.4,+0.0) (-5.4,+5.4) (-5.4,10.8)  0.298- 0 .345  988  4&6/5  (+5.4,-1.8) (5.4,-10.8)  6/5  (1.8,-10.8) (+1.8,-1.8) (+1.8,+5.4) (+1.8,10.8)  0.370- 0 .330  1224  7/5  (-1.8,-10.8) (-1.8,-1.8) (-1.8,+5.4) (-1.8,10.8)  0.360- 0 .327  1274  7&10/5  (+3.6,-5.4) (+3.6,+0.0)  Date day/month  Points  X start-end  (SSB)  10/5  (9.0,-10.8) (+9.0,-1.8) (+9.0,+5.4) (9.0,+10.8)  0.460-0.426  1142  19/6  (7.2,-10.8) (+7.2,-5.4) (+7.2,+3.6) (7.2,+10.8)  0.483-0.391  1638  7/7  (+0.0,-9.0) (+0.0,+9.0) (-7.2,+0.0) (+7.2,+0.0)  0.532-0.404  1342  8/7  (+0.0,-7.2) (+0.0,-1.8) (-3.6,+0.0) (+9.0,+0.0)  0.562-0.482  1370  9/7  (+0.0,-5.4) (+0.0,+3.6) (-10.8,0.0) (+1.8,+0.0) (+0.0,-1.8)  0.525-0.482  1524  18/7  (+0.0,+7.2) (0.0,-12.6)  0.684-0.491  1548  19/7  (+9.0,-7.2) (+3.6,-1.8) (+9.0,-5.4) (+3.6,+3.6) (+9.0,-3.6) (+3.6,-7.2)  0.700-0.530  1560  21/7  (0.0,-14.4) (0.0,+12.6) (-12.6,0.0) (12.6,+0.0)  0.682-0.505  1434  12/11  (+7.2,-7.2) (-3.6,+3.6) (+9.0,-9.0) (-1.8,+1.8) (+7.2,-3.6) (-5.4,-5.4)  0.503-0.425  1574  Date day/month  Note  total  of  integration  (10.8,-10.8) (-9.0,+9.0) (+7.2,-1.8) (-7.2,-7.2) (+1.8,+1.8) (-9.0,-9.0)  0.505- 0.485  1720  21/11  (-10.8,-10.8) 0.500- 0.425 (+5.4,+5.4) (-7.2,+7.2) (+7.2,+7.2) (-10.8,10.8) (+9.0,+9.0)  1870  days  ninety-five time  (SSB)  15/11  t o Lk HOO01 and was u s e d  source. Consequently,  and s e v e r a l  r  s t a r t -end  (5.4,-3.6) c o r r e s p o n d s  calibration days  Points  i t was o b s e r v e d  before the observation scans  o f 8.44 h o u r s .  were  collected  each  program giving  as  a  of these began. a  A  total  17  Figure  2 -Reference P o s i t i o n  The scans  figure  for  deviation spectrum  a  shown total  i s the average integration  from z e r o s i g n a l i s 0.75  kelvin.  noise  for  signal  i n the r e f e r e n c e  with  map  the average  Spectrum  positions  (dashed  is  n o i s e . The  6 ( 1 9 5 0 ) = 34°10 001 0 ,  a t 2.35  small  ,  second  h o u r s . The rms  n o i s e of  i s the average kelvin).  even  when  Ascension)  (Declination)  peak the  spectral The  12  CO  compared  reference position i s ,  (Right  M  2.5  k e l v i n . The  line  0^(1950) = 0 4 2 6 5 1 ^ 7 H  of  indicated  spectrum  spectral  time  i s -1.72  Also  of t w e n t y - e i g h t 320  19  11.4-On-Site Data  Handling  A Fabri-Tek minicomputer  was  details  of t h e  (1976).  Each  for  map  point  was  calibration.  The  temperature,  T  far  had  of  of  data  hardware  and  OFF  necessary made  are  No  the  on  the  same  at  the  i t i n our  by  Mahoney  was  four  ON-OFF  weighting  day  (Knapp  line. very  d a t a and  tape  et a l .  s t o r e d on pairs  according  u s i n g the  edge of our  this  same  to a sky  antenna  day.  Wilson  et a l .  structure  i n the  structure  would  b a s e l i n e s , we  consequently  for  an  for that  of v e l o c i t y  Although  to  1976,  1200  Complete  pair  s p e c t r a were c o n v e r t e d  the p o s s i b i l i t y  spectral  NOVA  s i n c e a l l the o b s e r v a t i o n s  , u s i n g the c a l i b r a t i o n  A  a  given  source  were a v e r a g e d .  by  handling.  o b s e r v a t i o n the  observations  appeared  evidence  day  controlled  on-site  and  averaged  indicated  wings of  have  each  were  Previous  for  source  position  the c a l i b r a t i o n  1973)  used  ON  After  single  averager  programs  papertape. each  signal  proceeded  found with  no the  analysis. The the to  last  spectrum those  (usually  s t e p of t h e p r e l i m i n a r y p r o c e s s i n g was  b a s e l i n e s by  p o i n t s of the  first  the 25  removing a second spectrum and  spectrometer). This allowed  us  last to  thought 22  correct  order polynomial f i t to  channels  calculate,  to  have  no  signal  of t h e  64  channel  20  where c i s t h e c h a n n e l number and S We a d o p t e d  Finally,  requires the  many  smoothed  line. of  data  spectra,  ( F i g u r e 18).  i n channel c.  deviation  f o r the  zero.  were n o t smoothed. Knapp e t a l . (1976)  Our r e s u l t s the  (rms)  t h e mean t o be  noted a s e l f - a b s o r p t i o n l i k e  in  i s the s i g n a l  c r a s t h e r o o t mean s q u a r e  spectrum. T h i s  spectral  c  feature  confirm  i n the middle  that  there  of  the  1 2  CO  i s a prominent d i p  w h i c h w o u l d be l o s t  i f the data  were  21  III.  DATA REDUCTION AND  ANALYSIS  III.1-Calibration This a  section  reliable  Absolute  discusses  calibration  calibration  procedure  to determine  believe  a maximum e r r o r Spectral generally signal This  absolute  i n a two  is  the  i s compared  temperature.  absorber  o b t a i n e d . The  temperature placed of  each  radio  A  calibration output  5 K r  , was  of t h e  T  The  end  a t t h e end  the  had  to an  the  change  insignificant  f l M B  atmospheric  opacity  from the  , and  calculated  by  The  the  was  measuring  liquid  ambient  nitrogen  temperature  done a t t h e b e g i n n i n g  of each  on  by  s e s s i o n . To we  the  T  S K  y.  two  ensure  interpolated  i n the r e f e r e n c e  changed  A  chopper  t h e sky  points defined  effect  T .  s o u r c e w i t h a known  between  f e e d h o r n . T h i s was  session.  observed  spectrum  temperature, T  an  are  approximation.  an a b s o r b e r a t t h e  were c h e c k e d  this  We  with  temperature,  from an a b s o r b e r a t an e f f e c t i v e  according  Generally  fairly  wavelengths  t o an a n t e n n a  d e t e r m i n a t i o n o f t h e sky t e m p e r a t u r e  results  where  at  to a c a l i b r a t i o n  ambient  observing  temperatures correct  at  of 85 K and  in front  is  i s f a r more e l u s i v e .  Rayleigh-Jeans  sky t e m p e r a t u r e ,  the d e f l e c t i o n s  scale.  g i v e n an a b s o l u t e s c a l e  synchronously detected d i f f e r e n c e wheel  scale  step process. F i r s t ,  converted  assumes  signal  temperature  temperature  observations  calibrated  intensity  observed  finding  o f 20 p e r c e n t . line  process  relative  method has  our  in  wave o b s e r v a t i o n s i s more o f  but an a b s o l u t e s c a l e  our c a l i b r a t i o n  encountered  for  for millimetre  an a r t t h a n a s c i e n c e . The easy  the problems  the  end  points.  On  nights  dramatically  the  sky  22  temperature was  correction  monitored  carried  second  antenna  The  atmospheric  beam e f f i c i e n c y , ^  standard sources  for  the true b r i g h t n e s s  measured T  at v a r i o u s  A  values (Ulich  start  a full and  S K  tipping  finish  of  process i s to c o r r e c t  the  of  T  , was  for  A  and Haas  and  antenna  losses  to  temperature. calculated  s e c a n t z's  millimetre  difficulties  by  comparing  our  (z i s t h e z e n i t h a n g l e ) t o t h e  0MC1(Orion  1976). We  A)  and  determined  wavelengths  in determining  particularly  true  the s i g n a l  as a f u n c t i o n  several  t o be  The  is  on  this  method  causes  zenith  attenuation,  tipping  c u r v e s are used relationship  Two  c a n be  The f  1 2  related  C0  s  other  about  37  number  of  This  is  losses.  how  requires  attenuation  to the average  attenuation  sky t e m p e r a t u r e . the s i g n a l  and  There  and  the  to  line  frequency  a b s o r b i n g oxygen  image  determine  X  s  and  t;  line  different  the  signal  attenuation,  X{ . Our  t o measure t h e a v e r a g e  between  is  image g a i n s  bands t o have s i g n i f i c a n t l y is  a  the  J=1—'0 s p e c t r a l  problem ,  a  o b s e r v a t i o n s . One  of a v e r y s t r o n g l y  t h e two  attenuations.  attenuation  C0  determine  115.271 GHz  zenith  a  be  to  the t a i l  are  atmospheric  of z e n i t h a n g l e , z, and  separately.  and  1 2  there  s i d e b a n d g a i n s and  s i d e b a n d can  convenient  situated  the  f o r J=1—>0  knowledge o f t h e r e l a t i v e  If  and  T y  cent. At  no  out a t t h e  s t e p i n the c a l b r a t i o n  temperature  determine  in  hour  error.  observing session. The  per  a potential  approximately every half  c u r v e measurement was each  helped eliminate  is  attenuation, known, t h e  X  •  signal  found.  summer s t u d e n t s a t U.B.C. have worked on  this  problem  23  for  our  telescope.  (1980) on c a l i b r a t i o n for  From  an  internal  procedures,  report  by R o b e r t Braun  we have an e m p i r i c a l  relation  X .  the average a t t e n u a t i o n  r =. — ! — in \(\+0.0\3L7 Sed l)flbg. ]*38. \\'\*(T^ r^S)(\~ Sec 2 l  L  Sec  <  <  t  where  c J  _ E  C  '  £  Here  C  O  j  I E  5  DEC  cos  (DEC)  of T  secant The  A  versus  m  relation  s i x values  Knowing Bruyn  =  7  for  T  ,  our t i p p i n g  of secant  varying  -  (49°25  North).  angle  By making  T „ (270,280,290,300) A  we on T  6  for r  solve  A M 6  %  values  dependent for T  A r l 6  X .  from a p r o g r a m d e v e l o p e d by John de 'Atmosphere'  relates  considerations.  o.ooa) T  and  graphically.  and s t r o n g l y  c u r v e s we o b t a i n e d  ( 1 9 7 9 ) . De B r u y n ' s p r o g r a m  (LO«I  (DEC) S I H ( L )  z ' s and t h e n u s e d t h e g r a p h s t o f i n d  we o b t a i n e d  from t h e o r e t i c a l  r  of the t e l e s c o p e  i s weakly dependent  z. From  ( L ) + S\n  o f t h e s o u r c e , HA i s t h e hour  z (1.0,1.1,1.3,1.6,1.8,2.2)  on s e c a n t at  (HA) C O S  i s the d e c l i n a t i o n  and L i s t h e l a t i t u d e plots  COS  +  —8\  (o.ia3  ± ^ >o x  )  and T-  L  24  and  r.  =  (o.ioq  As  we  between  can t  see  give  from  from  calibration  assumptions  -  ±a*icf )  (0.113  8  t h e s e e q u a t i o n s we have a l i n e a r  Unfortunately,  good  significantly our  o.oox)r  and "~t.  s  always  ±  results.  T  this (  A  1 2  relationship C0)  for  required  likely by  arise  this  from  d i d not  0MC1  t h e a c c e p t e d v a l u e o f 60 K. The  errors  relation  varied  majority  of  some o f t h e s i m p l i f y i n g  program  (eg. a p a r a l l e l  plane  atmosphere). Once  was  determined  Sec atmospheric antenna  losses  (£  temperature,  temperature,  T  A  we  ,  )  T  for  ,  A  could  correct  T  for  A  both  Z and  and  the  the  a parallel  beam l o s s e s  true  source  ( ^ ) • The brightness  plane atmosphere a r e r e l a t e d  by,  T  A  = T:  Our  data  different  %  ex  for  ( - ?  ?  First,  attenuation,  z)  sec  Sharpless  methods.  atmospheric  s  222  were  calibrated  we c a l i b r a t e d  X  ,  from  - our  tipping T  OMC1(Orion A) was 55 ± 9 K where t h e 9 r e f e r s  to  The  average  two  a l l the data using the  temperature,  measurements.  using  A  (  1 2  curve  CO),  the  for  standard  25  deviation T* ( ft Lk  1 2  of  any  C0),  HOI101  one  for  measurement.  our  (5.4,-3.6),  The  second  was  then  average  calibration  found  o f t h e mean o f 0.5 K. S e c o n d , we c a l i b r a t e d  data  this  This  spectra.  averaged  are  given  map  H o n 01  Lk  lower  that  H o n 01  the  average  had that  the  (5.4,-3.6)  T  (  A  1 2  t  this  s  from  CO)  telescope remainder  raw  Sharpless  temperature o f 0.5  for  K.  calibration  (7.2,-3.6)  for this  The  source  This  results  appears  i t  the  we  scaled  (0.0,-3.6)  calibration  a  have  been  technical  project  calibration  the  that  T  A  D.C.  CO)  1 2  T* (  1 2  of  CO),  using  spectrum  at  i n the  offset  that  of the spectrometer. this  spectrum  Unfortunately,  difficulties  prevented  much t o o  located  to a l t e r  repeated.  (  i t  source  was c o r r e c t e d  s o u r c e . The  random  After  observed  was i n f a c t  be  These  (7.2,-3.6).  t o have a bad c h a n n e l from  to  spectra.  day up t o t h e a v e r a g e  t h e r e was no e v i d e n c e  experienced of t h i s  of  i n one o r two c h a n n e l s  should  appeared  t h e s e were  (0.0,-3.6)  Lk H o n 01  appears  that  Lk HCX101  and  anomaly  the scaled  was d e c i d e d t h a t that  the  of the surrounding  temperature  1 3 . 5 K. The p o i n t  HW101  taken.  case  f o r Lk H o n 01  (5.4,-3.6)  periodically  and  calibrate  (0.0,-3.6)  correct  profile.  It  than  (5.4,-3.6)  To  new  t o use t o  t h e d a t a on t h e two d a y s t h a t  found  namely the  positions  Lk H«i 01  examining  Lk  same  C O ) f o r O M C 1 ( O r i o n A) t o be 6 0 K.  o f o u r Lk H « 1 0 1  plots  considerably  low.  this  the  i n F i g u r e s 3 and 4.  Two  were  s  1 2  was 1 3 . 5 K w i t h an rms e r r o r  _  two  Lk  In  (5.4, 3.6)  H0(101  was  T* (  gave a new v a l u e o f X  222 Lk  setting  source,  t o be 12.8 K w i t h an rms  error  time  temperature,  throughout  any more s p e c t r a  the the being  26  During component  four  sessions  atmosphere t h a t  our  was  component  had  result  calibration errors  the  estimate  dependent  a d i f f e r e n t atmospheric  that  conclusion,  t i p p i n g curves  the  we  error  believe  not  bulk  of  error  several  p o s i t i o n s confirmed  very  tricky  precautions precautions For  procedure to  maintain  helped  millimetre  procedure  20  does  per  that  s i m p l i f y and wave  radio  i s e s s e n t i a l t o good  our  data  estimate.  T  as  r e d u c e our astronomy  , and higher.  per has  cent. a  a We In  maximum checks  at  Calibration is a  consistent  r e s u l t s . We  data.  Each  were 20  two  angle.  Repeatability  requires  reliable  days exceed  cent. this  zenith  attenuation,  for these  calibration grid  of  the  on  indicated a  feel  checks  and  that  a l l the  calibration  errors.  careful  calibration  27  Figure  3 -Lk HCXIOl  This  spectrum  s c a n s . The t o t a l coincides  ( 5 . 4 , - 3 . 6 ) - T i p p i n g Curve is  the  integration  with the e x c i t i n g  average time  star  temperature  was  M  calibrated  m e a s u r e m e n t s . The v e l o c i t y scans  (rms e r r o r  hours.  (Right  location  Ascension)  (Declination)  using  the d a i l y  i s the average  o f t h e mean  The  320 s e c o n d  Lk H<X101,  S ( 1 950 ) = 3 5 ° 1 0 ' o o ! ' o  The  of n i n e t y - f i v e  i s 8.44  # ( 1 9 5 0 ) = 04 2 6 5 1 ! 7 W  Calibration  for  i s 0.07 km s " ) . 1  tipping  curve  a l l ninety-five  29  Figure  4 -Lk H«101  This  spectrum  s c a n s . The coincides  (5.4,-3.6)-OMC1(Orion  total  is  the  integration  w i t h the e x c i t i n g  CXO 950)  average time star  f1  temperature  calibration 60 K. The error  was  s o u r c e . T*  (Right  5  velocity  calibrated (  1 2  km  s  _ 1  The  second  location  Ascension)  (Declination)  using  OMC1(Orion A)  C O ) f o r C M C 1 ( O r i o n A) was  i s the average  of t h e mean i s 0.07  hours.  320  Lk HCX101,  6 ( 1 9 5 0 ) = 35°10'001'0  The  Calibration  of n i n e t y - f i v e  i s 8.44  = 04 26 5l .7 H  A)  ) .  as  taken to  for a l l ninety-five  scans  the be (rms  LH101 ( 1 ECO  5. 40.  PERK TEMP VELOCITY RMS N 0 I 5 E  T  - 1 9  - 1 3  -7  1 - 1 19* ( K M / S E C )  -  1 1  -3.6D)  13.5 -1 .25 0. 3B  17  LO  O  31  III.2-Representation We  present  complementary (DEC)  versus  second did  Sharpless  formats. right  is  that  not  have  have c o l o u r  and  Figure  antenna  with  using  Figure  v e l o c i t y . The 5 and 6. We  computing  can  found  not  for  calibrations  at  centre  these  does were  distinguish  the  of  the  on  simple  plot  the  of  In  using  the  One  better  than  we d e c i d e d  details  as  this  gain  positions  determined  (5.4,-3.6)  from t h e Lk H O U 0 1  calibration  of the s p e c t r a l p o s i t i o n s source.  been  the c a l i b r a t i o n from  t o use t h i s  are given  way we  spectral  has  those  positions  correction,  Lk H 6 X 1 0 1  OMC1  is  formats.  transparency  (0.0,-3.6)  i t  f e a t u r e s and t h e i r  OMC1(Orion A) a s a c a l i b r a t i o n position  showing  different  well.  i s the g l o b a l p l o t  t o be s l i g h t l y  Full  very  measurements.  made  reason  advantage  p l o t s show t h e s m a l l e r  the atmosphere  6  correction  analysis.  line  p a c k a g e . The c e n t r e  features  global  i s based  using  this  p l o t s of d e c l i n a t i o n  (1980)  eye  in relatively  tipping  calibrated  For  different  f e a t u r e s q u i t e w e l l ; however  position  5 i s the  (0.0,-3.6),  found  Szabo  human  general  The c o n t o u r  calibrated  two  U.B.C.  graphics  contours. the  information  source.  colour  the  p l o t s have t h e d i s t i n c t  correlations maximum  since  t o see how s m a l l e r  correlate.  i s contour  (RA) f o r a f i x e d  contours  a full  region  difficult  in  properly.  Global entire  ascension  since  intensities  results  The f i r s t  intensity  unsuitable  222  Plots  o f g l o b a l p l o t s a s shown i n F i g u r e s  not use c o l o u r  does  Of Lk H o n 01 T h r o u g h G l o b a l  i n chapter  made.  The  source  were  the t i p p i n g  data IV.  The same  f o r the  curves. remaining  32  Figure  5 -Global  All  -23  scale  to  24  1  Lk  (0.0,-3.6).  central  using  spectral  km s " .  (5.4,-3.6)  calibrated  Curve  i s 95.00 K i n  Lk H<X101 H0HO1  (Tipping  eighty-nine  temperature is  Plot  There  positions -  the  is  indicated.  one c o r r e c t i o n  source.  remaining  daily  are  a n d t h e L.S.R. v e l o c i t y  1  calibration The  Calibration)  tipping  This  spectral curve  is  = 04 26 34 .O H  M  s  5 ( 1 9 5 0 ) = 35°13'00i'0  (Right  range on t h e  position  positions  measurements.  position i s ,  (XO 950)  based  Ascension)  (Declination)  The  were The  33  LH101  MM  •Ax*:  UUxJ UU  UJ  Uw  UJ  UJ  UJ  U*  "T^TB  nr-F"  -ri  r*B  =rf~D  SIGHT RSCEHSION  IflRCNINSl  i£r  ^rr  =£D  ^tn  34-  Figure  6 -Global  All  Plot  eighty-nine  temperature  scale  to  24  -23  Lk  H«101  (5.4,-3.6)  Lk  HW101  (0.0,-3.6).  calibrated (  1 2  CO)  position  km  using for  spectral  i s 89.80 K  is  T*  ( 0 M C 1 ( O r i o n A)  s  .  - 1  in ~  There  positions and  1  is  calibration The  was  taken  the one  are  correction This  spectral  as  the  to  be  indicated.  L.S.R. v e l o c i t y  source.  remaining  OMC1(Orion A)  OMC1  Calibration)  is  k e l v i n . The  =  04 26 34. 0  8(1950) =  H  M  S  35°13'00"0  (Right  Ascension)  (Declination)  the  position  positions  is,  o(( 1950)  range  b a s e d on  calibration 60  The  were  source. central  WW  *Av*  ."t*A»* f»Av -»A*ft;  LA*  L A .  *A*:  -I±B  nto  r"D—  —  = 0  ^r  RIGHT nscrasiw IRROIINS)  -  *  =+s  ^  =An  36  III.3- CO  Radiation  1 2  The  velocity  Temperatures  resolution  available  is  determined  b a n d p a s s o f t h e s p e c t r o m e t e r . Our s p e c t r o m e t e r of  250  km s  -  used 125  KHz  which c o r r e s p o n d s  a t t h e J=1—*0 t r a n s i t i o n  1  to  check  the c r y s t a l  KHz. The main r e a s o n  frequency  itself.  continually  To  for this  such  exceeded  125  KHz.  corrected  lies  i n our L o c a l  The  velocity  from  the observed  i n Mahoney when  (1976),  calculating  of  problem  channel.  Summing o v e r  see t h a t  the t o t a l  i n f o r m a t i o n . Our  the p o s s i b l e  error  error  (L.S.R.)  days  one h a l f  program.  described  into  account  h a s shown a  that  spectrometer  s o u r c e s of v e l o c i t y  i s a t the l i m i t  been  i s subtracted  program,  Julian  was  never  has s u b s e q u e n t l y  of Rest  than  crystal  the counter  the e a r t h ' s motion  i s less  counter  the  resulting  that  d i d not take p a r t i a l  incurred  widths  i s a c c u r a t e o n l y t o about  the  Standard  the  o f 0.65  frequency  t h e L.S.R. S u b s e q u e n t a n a l y s i s  t h e maximum e r r o r  is  The  this  error  from  velocity  CO.  resolution  i s the d r i f t  that  Another  resulting  1 2  frequency  minimize  monitored  has f i l t e r  to a velocity of  by  errors  of our r e s o l u t i o n .  we  This  0.65 km s " ' . In  for  determining the c e n t r a l  Sharpless  difference  222  we  used  velocity two  of t h e s p e c t r a l  independent  methods.  and  OMC1(Orion A) a t t h e b e g i n n i n g o f o u r o b s e r v i n g p r o g r a m was  such  we  could  just  f i t both  b a n d p a s s u s i n g t h e same c r y s t a l switching  between  Since  know  we  two l o c a l  the  spectra  into  frequency.  oscillators  frequency  for Sharpless  The  222  that  between t h e L.S.R. v e l o c i t i e s  profile  This  spaced  difference  the spectrometer was  done  by  8.0 MHz. a p a r t .  between  the  two  37  oscillators resulting for  the  1 2  t o a h i g h degree  S h a r p l e s s 222 p r o f i l e C0  profile  velocity  for  position.  The  place  of a c c u r a c y we  a line  velocity  velocity.  could calculate  We  assumed  i n 0 M C 1 ( O r i o n A) of 9.0  Sharpless second  222  method  having V  L S R  f o r Lk HcnOl  o f -1.25  used  = 0 km  s  km  km  s  _ 1  a crystal into  _ 1  (5.4,-3.6) was  s  - 1  a  frequency  found  velocity  . T h i s gave a  f o r the  channel  the  (5.4,-3.6) designed to  33. The  t o be -1.25  central km  s  as  - 1  before. The  spectral  profile  f o r OMC1(Orion  wide. A d o p t i o n  of a c e n t r a l  wide  w o u l d n o r m a l l y have a l a r g e  profile  the v e l o c i t y defined as an  t h e c e n t r e o f a wide  of a narrow  line.  the primary  calibration  s o u r c e we  average km  0.25  km  9.0  central  s ~ . The 1  s  - 1  km  We  have  a  total  (5.4,-3.6). -1.25  km  s ~ . The  km  s  1  km  s  standard deviation  velocity  Knapp  both  sets  a  et a l .  f o r Lk H0M01  i s in excellent From  by  i s n o t as A)  with  precisely was  used give  w i t h an rms  error  of  f o r any one measurement  was  w i t h t h e assumed  that  two  determined  error single  of  two  (1976)  obtained  222. source  from  these  i n t h e mean o f measurement our  a  central -1  ±  0.07  i s 0.33  than  (5.4,-3.6) o f a p p r o x i m a t e l y w i t h our  value  different  f o r the c a l i b r a t i o n  rms  of d a t a c a l i b r a t e d  very  for Sharpless  velocity  o f any  1  factor  agreement  associated  a  s~  velocity  an  such  1  that  95 s c a n s  with  _ 1  on  1  s~  36 p r o f i l e s  be n o t e d  The a v e r a g e  which i s l e s s  resolution.  of  s~~  error  line  very well  gave t h e same c e n t r a l  is  - 1  agrees  km  5 km  have  km  standard d e v i a t i o n  . This result  i s about  S i n c e OMC1(Orion  of 8.92  1  Lk H0(101 scans  velocity  s~ . I t should a l s o  procedures  This  of 9.0  as t h a t  0.04  of  since  velocity  A)  velocity profile  1 km  s" . 1  results. u s i n g t h e two methods  we  38  obtained  T  A  (  1 2  C0)  contour  maps  Comparison  of these c o n t o u r s  identical.  F i g u r e 7 shows t h e T  for fixed  indicates A  (  1 2  that  L.S.R. v e l o c i t i e s .  they a r e very  C 0 ) contour  map  nearly  integrated  o v e r a l l L.S.R. v e l o c i t i e s . To fixed  check  velocity  features  T  could and Due  A  by s m a l l i n c r e m e n t s . We  were  resolution. the  the. r e a l i t y o f t h e c o n t o u r  (  1 2  negligible,  The s p a t i a l C0)  be c a u s e d  contours  to this  spatial  Full given  fact,  details  is  found  far less  o f most o f  i n the  than  our v e l o c i t y  the  features  on  only marginal. Unresolved features calibration  the r e a l i t y of these we c a n n o t  the changes  f o r one  grid  position  f e a t u r e s may be s u s p e c t .  s a y v e r y much a b o u t  the s t r u c t u r e or  of S h a r p l e s s 222.  details  i n chapter  resolution  by i n c o r r e c t  consequently  certainly  f e a t u r e s we v a r i e d t h e  of the s t r u c t u r e four.  and s i z e  of  our  cloud  are  39  Figure  7 -Integrated  The  T^  (  Figure  7. The  shows  the  C0  Contours  C0) i s integrated  declination  five  (0.0,-10.8), for  , 2  1 2  hottest  (7.2,-5.4),  both a x i s  (DEC)  over  versus right  spots  = 04 26 34!o  5( 1 9 5 0 )  to  be  ( 3 . 6 , - 5 . 4 ) , and  a r e a r c m i n u t e s . The  6VO950)  a l l  H  M  = 35°13'00'.'0  velocities  to  a s c e n s i o n (RA)  located  at  plot  (7.2,-10.8),  (0.0,-1.8).  centre  (0.0,0.0) i s ,  (Right  Ascension)  (Declination)  give  The  units  4-0  RA. ARCMIN. °!2.0  i  •2.0  9.333  i  9.333  6.667  1  6.661  4.0  I  4.0  1.333  1  1.333  -1.333  •  |  -3.333  Rfl. ARCMIN.  -4.0  1  -4.0  -6.66-7  1  -6.66T  -9.333  1  -9.333  -12=0  |-V  -32 0  41  I I I . 4 - G e n e r a t i n q Model F o r Although can  we  C0.  It  Two s i m p l i f y i n g  need  temperatures.  must  be  emphasized  and  reinforce  are  the  of the  1 2  C0 to  we r e q u i r e t h e p r o f i l e  not  o b s e r v a t i o n s . As a r e s u l t , to  a s s u m p t i o n s have t o  t o know t h e r a t i o  Secondly,  approximation  C0  C 0 o b s e r v a t i o n s were n o t made, a p p r o x i m a t e  be g e n e r a t e d .  First,  1 3  1 3  1 3  that these  a  good  half  data  1 3  made.  C 0 emission widths  for  a r e o n l y a rough  substitute  the generated  conclusions  1 3  be  data  C 0 data  apparent  for  real  a r e used  from  only  the  1 2  CO  observations. In o r d e r require for  that  f o r the  1 3  1 3  (  lower 1 3  three  than  CO) versus  1 2  CO  that  CO)  and  ratio  temperature,  1 3  of  from CO  other  we  can  Sharpless  f o r the (  A  1 2  1 2  1 2  estimate  1 3  CO),  r e g a r d . He  by  found  i n shape and  approximately  five  C O . F i g u r e 8 i s a p l o t of  CO)  to  T  A  (  1 3  (1980).  The r e s u l t i s  both  ratio  two  positions.  temperatures f o rSharpless  i s five.  t h e m a g n i t u d e and v a r i a t i o n of other  The This  222 b e h a v e s  r e g i o n s s t u d i e d by S e w a l l  222 u s i n g t h e r e s u l t s  an  f o r the  C O ) . Knapp e t a l . (1976) o b s e r v e d 222 a t  to give  CO)  for  radiation  Sharpless  (  estimate  i n Sharpless  their  A  we  obtained  1 2  were  C0),  1 3  T  data  the CO p r o f i l e s  t h a t c a n be u s e d  our T * (  C0,  in this  r e g i o n s s t u d i e d by S e w a l l  the temperature  the  beneficial  of T  1 3  Recent  temperatures  the r a t i o  Sharpless  1 3  C0 radiation  positions.  those  a power law r e l a t i o n (  of  C O p r o f i l e s mimicked  the CO r a d i a t i o n  times  T*  1 3  T (  the opacity  (1980) have been v e r y the  that  A  values  each of the s p e c t r a l  Sewall  T  to calculate  (1980). of t h i s  Sharpless  average indicates  much  like  Therefore, ratio for  regions  from  42  Sewall ratio  (1980). of T * (  values  1 2  The  estimates  CO) to T  (  A  within  a  1 3  given  a r e summarized i n T a b l e  C O ) was  range  of  assessments of the i n t e r p o l a t i o n extent ratio  of  the  of  low  amounts. The  approximations. as S h a r p l e s s CO  emission  observations  ratio  f o r the  Extending  222 s h o u l d  were  1 3  was CO  within  -1.25  km s  clearly 1 3  CO  in  25 -  1  emission.  t h e next Using  Some s u b j e c t i v e  according  and  t o the areas the  f o r very  small  i n c r e a s e d by t h e same  t h i s method t o i n d i v i d u a l  o n l y be done a s a l a s t  are  rough  sources  such  r e s o r t . Data  from  a r e always p r e f e r a b l e .  per  cent.  us t o e s t i m a t e  The r e s u l t s  are i l l u s t r a t e d  shows  CO).  temperature  We b e l i e v e t h i s method h a s e n a b l e d to  1 2  made  by 0.1 t o 0.2  the  estimates  T* (  The  interpolated for  regions. For large emission  was u s u a l l y d e c r e a s e d  areas  1 3  emission  linearly  II.  in  Figure  t h e h o t s p o t s embedded These r e s u l t s  o f t h e peak T  will  9.  This  A  T* ( (  1 3  1 3  CO)  CO)  contour  for plot  i n a c o o l e r background of  be d i s c u s s e d  i n greater  detail  chapter. derived values  from t h e s t a n d a r d  f o rT  A  (  1 3  C O ) , we d e t e r m i n e d  ?^( CO) 13  formula,  X ( cd) =• ~ [h  This  equation  temperatures true  assumes  that  the  a r e e q u a l . One e x p e c t s  b u t a s we w i l l  see t h i s  may.not  CO  and  this  to  1 2  be v a l i d  1 3  CO  be  excitation approximately  whenever t h e r e i s  43  a distinct levels  d i p i n the s p e c t r a l  of  the  excitation the  local  thin  1 3  This  gas k i n e t i c This  is  that the  above a r e a c t u a l l y The VI  for  1 2  C0  i s probably  temperature  results  following this  1 3  C0  lower  T * (  than  due t o t h e f a c t  trapping occuring with  means  The e n e r g i e s  isotope species are very  temperature  CO.  radiation  two  profile.  1 3  limits  C 0 ) and  chapter.  that there  calculated  of the r e a l f(  1 3  CO)  and c l o s e r t o  of  the o p t i c a l l y  opacities  J=1  n e a r l y e q u a l . The  larger  that  of t h e  the  optically  i s significant  thick with  1 2  C0  line.  the formula  value.  a r e summarized  in  Table  4/4-  T  ( C0) (kelvin)  Ratio  12  A  (  i a  >20  II - T J(  Table  Table T  A  an  (  1 3  CO)  10—16  5.0—4.0  <10  7.5 — 5.0  C O ) Generating  for different  analysis  (1980).  4.0 — 3.5  details  of  data  (  1 3  CO)  <3.5  16—20  1 3  II  CO)/T^  Model  estimates  of  v a l u e s of T * ( on  Sharpless  1 2  the  ratio  T * (  CO).  These  result  regions compiled  1 2  CO)  to  from  by S e w a l l  4-5  10 ^0 0  r 10  O C  0  l  0 0"  \o° o ce  <n > H rH  e  E-  1  .\  \ \  0  2  4  \  6 3 Ratio ( C0)/T * ( C 0 ) 12  U  1 3  A  Figure  8 -T* (  The Circles and  ratios  Model).  C 0 ) V s . T* ( C O ) / T * ( 1 2  were  are Sharpless  boxes  generate  1 3  are the  obtained  1 3  C0) Ratios data  of  Sewall  152 d a t a , c r o s s e s a r e S h a r p l e s s  Shapless  T*(  from  1 3  C0)  148  data.  This  result  (see  Table  II-T*(  , 3  C0)  206  (1980). data,  was u s e d t o Generating  4-6  Figure  9 -Generated  The  T  A  (  1 3  T  f t  CO)  (  1 3  contours  o b s e r v a t i o n s . The c o n t o u r (DEC) hot for  verses right spots  present  C 0 ) Contours are  generated  from  1 2  C0  u n i t s a r e 0.5 K s t e p s . The d e c l i n a t i o n  ascension  (RA) p l o t  i n Figure 7 ( T *(  shows t h e 1 2  H  M  (Right  5  6 ( 1 9 5 0 ) = 35 13'00'. 0 d  /  five  CO  C O ) C o n t o u r s ) . The u n i t s  b o t h a x i s a r e a r c m i n u t e s . The c e n t r e  CX( 1 950 ) = 0 4 2 6 3 4 . 0  same  (0.0,0.0) i s ,  Ascension)  (Declination)  47  48  III.5-Generated To N  COL(  1 3  the  we  we  1 3  and  1 3  S148  estimate  C0  to study  for other  C0  profiles.  Sewall  t o two  (1980).  ratio  AV(  1 2  d e v i a t i o n of  error  0.04  of We  we at  the  89  assumed  random. The t o be  half  widths.  gaussian  20  have  gaussians  observed reduce  the  reduces  the  summary o f Once  To  peak  the AV(  two 1 2  observed  the  line  given  of  i n our  corresponding i f there  widths  in Table  for  C0  1 2  I I I . S152  and  taken  Knapp e t a l . ( 1 9 7 6 ) .  1 3  from  CO), one  adopted  studied  was  1.52  measurement  from the  from  larger  than  t o measure  the  be  by  with  or  an  a  rms  C O ) was  this  too  chosen  profile  visually  f i t f o r our  was  measured since a  data.  The  f a r w i t h a net  result  of  peak t e m p e r a t u r e  of  the  The  alternative  Unfortunately,  this  i s to also  deemed u n a c c e p t a b l e .  in Table  visually,  for  method  profiles  1 2  w h i c h was  i s given  found  of  AV( CO) v i s u a l l y  i f the  gaussian.  profiles  gaussian  the  maintained.  temperature methods  the  a good  that extend  to  spectral  accuracy  CO)  1 2  o b v i o u s l y not  is  our  f i t t o s i x of our  becoming t o o wide  of  power  check  AV(  cent  wings  width  widths  regions to determine  i n any  decided  profile  line  not  and  density,  regions  AV(  gaussian  ± 2 per  was  power  was  C0  column  Sharpless  CO) visually  best  We  C0  average.  resulting  profile  gaussians  1 2  to  positions.  the  found  the  AV(  S239 a r e  C0  1 2  are  three  0.10  i n the  found  e a c h of  results  CO)  standard  of  1 3  half  1 3  Sharpless  S222 and  ,  pairs  the  the  Since  between h a l f  The of  for  f o r the  profiles.  a relationship  refer  The  an  decided  profiles  exists  Column D e n s i t i e s  require values  expected  C0  C0  obtain  CO),  survey 1 3  1 3  AV(  A  IV. 1 3  C O ) was  determined  49  by  dividing  AV(  CO)  1 3  each  AV( CO)  e x  W C0) J  (  CO)  1 3  ex  used  notes  once more  time  the  ^(^CO)  are  expression  the  for  ( C O ) =. T  are  1 3  to  1 2  C0,  N  as  error  is  C O L  (  1 3  CO),  quoted  in  t 0  ( CO) = T  t h e column  together  3  density  C O L  three  well  (  1 3  CO)  the  cloud  were t r e a t e d i n t h i s  column  We  CO.  and  1 3  As  density long  as  assumption very  nearly  limit. believe  there  # 1 , # 2 , and #3. They a r e (0.0,-10.8),  Another  two  limit  of  our  and  possible  p r o j e c t . Extreme c a r e  a r e on t h e v e r y  1 3  e x  i s a lower  Lk H6X101  respectively.  for  T .( CO)  should  t h e column d e n s i t i e s .  (7.2,-10.8),  e x e r c i s e d s i n c e they  the  must  sense as t h a t  reduced.  errors  estimate  resolved clouds:  (7.2,-5.4)  Since  in  ( CO) 12  e><  seems t o be a r e a s o n a b l e  then  10 r e p r e s e n t s  HOH01  ,3 j  3 o )  13  e y  substantially  which  the N  Lk HCX101  T  (  opacity calculation.  Figure  at  T  i n c u r r e d i s i n the o p p o s i t e  multiplied  otherwise  - ; y  U [ l  the assumption  regions,  fragmentations be  CO  13  e x  Sharpless  located Lk  1 3  ( CO) ,  1 2  cancel;  that  error  i n the  e/  for  AV( CO)  d e r i v e d by M o r r i s  in calculating  introduced  T  density  of  i s c a l c u l a t e d from,  = T M=5.53  Morris  This  a relation  ratio  (1980).  where T  be  the  ( i . e . 1.52). The column  was c a l c u l a t e d u s i n g Sewall  by  1 2  should spatial  50  resolution. clouds, Lk  is  HCX101  #4  Examination and  are  (3.6,-5.4) and  It  cannot  only  an  h e a v i l y . The p r o g r a m and our  #5,  of  be  as  CO  12  probably Lk H«101  emphasized  approximation 12  the  fragmentations  are  profiles  real.  They  enough t h a t and  real  on  are  these  located  should  the generated not  be  t h e b a s i s of  t h e v e r y c o r e of our  appear  indicates  at  (0.0,-1.8).  o b s e r v a t i o n s form  such  CO  the  12  CO  13  relied our  CO  data  upon  too  observing  c o n c l u s i o n s . A l l of  global  plots.  5I  Source  Position  S152  W1S1  5.4  3.7  1.47  E1S1  5.0  3.2  1.55  S148  E0S1  3.9  2.8  1.40  S222  E0N0  4.0  2.7  1.49  E0N1  3.6  2.1  1.70  E0N0  2.5  1.4  1.59  E2N0  1.6  1.0  1.46  S239  AV( C0)  . AV(  12  average—  Table  III - P r o f i l e Our  observed regions AV( our  1 2  C0)  1 3  1 2  C0  CO  profile  survey  the average  half half  et a l .  to AV(  1 3  CO)  1.52.  widths  1.52  Ratio  ±0.04  were c a l c u l a t e d  widths.  1976,  Data  Sewall  i s remarkably  was d e t e r m i n e d ratio  CO)  (rms)  Half Width R a t i o s  profile  Knapp  1 3  for  1980)  four  show  c o n s t a n t . The  by d i v i d i n g  the measured  u s i n g the Sharpless  t h e r a t i o of AV(  1 3  AV(  CO) 1 2  in  C 0 ) by  52  Parameter  Method Gaussian  Visual Veloc i t y  D i r e c t l y from spectral plot program, same as g a u s s i a n .  Standard deviation  D i r e c t l y from spectral plot p r o g r a m , same as g a u s s i a n .  AV{ CO)  Table  <1%  ill  Visual est.  1J  D e v i a t i o n between t h e two methods.  sTL-  AV-2U  <1%  1  loq 2' cr  high  e  20f o±r g2% aussian  IV - V e l o c i t y C a l c u l a t i o n s This  data  the v e l o c i t y profile,  summarizes t h e two a p p r o a c h e s u s e d  of each p r o f i l e ,  and the p r o f i l e  inspection  and  gaussian  obtained  for profile  fit  high  is  sharpness  by  half  about  of the observed  much f l a t t e r  than  representations  half  the  standard  widths.  fitting  resulted  The v a l u e  twenty  per  profile  shapes.  of the observed  deviation  only  of  from  cent.  This  Gaussian  for the  each visual values  gaussian  i s due t o t h e curves  p r o f i l e s and a s a r e s u l t data.  determine  D i f f e r e n c e s between  widths.  the observed  to  are  a r e poor  53  Figure  10 G e n e r a t e d  The  N  C O L  (  1 3  observations. declination same  five  The  units  the (see  ratio  N  C O L  CO) The  (  1 3  CO)  Contours  contours  are  contour  (DEC) v e r s u s  right  CO h o t s p o t s p r e s e n t  units  generated are  ascension  AV(  Table  1 2  CO)  to  Ill-Profile  AV(  1 3  1 x 10 (RA)  CO)  was  1 5  1 2  H a l f Width R a t i o s ) .  to  be  6 ( 1 9 5 0 ) = 35°13'00'.'0  (Right  Ascension)  (Declination)  cm" .  The  shows  the  N  t O L  1.52  The c e n t r e  is,  Of ( 1 950) = 04*26*34*0  CO  CO) Contours).  To d e t e r m i n e  found  1 2  2  plot  in Figure 7 ( T * (  f o r both a x i s a r e arcminutes.  from  (  1 3  C0),  +0.04  (0.0,0.0)  54  55  III.6-Star  Counting  The  basic  described of  the  grid the  grid  Palomar  from b o t h  for star prints  prints  s e t s of p r i n t s  s q u a r e s was p l a c e d  u s e d was 1.8 a r c m i n u t e s . points  of  This  our t e l e s c o p e  counting  and  the  i s that  originals  were u s e d  f o r the star  agreed. A  transparent  on t h e p r i n t . is  the  The s i z e o f  spacing  between  beam a n d a l s o t h e s p a c i n g the  a i d of  a  low  microscope. All  their  s t a r s i n a given  s q u a r e were c o u n t e d  without  m a g n i t u d e s . T h i s was a d o p t e d b e c a u s e t h e s m a l l  would  have  introduced  t h e s m a l l number  magnitude. stars  in  The any  Star  i s fr\  outside  used.  The  regions  extinction  i n the cloud.  leads  in selecting  obscuration. repeated  Star  f o r both  the region presence to As  1937).  fields  with with  a  of  Star  o f 'n'  counting  was  were made i n e a c h o f  any  considerable  counting  each  of  Palomar i n the  underestimate  to minimize  c o l o u r s . The l i m i t i n g  Both  obscuration  field  and  size  particular  a count  of o b s c u r a t i o n .  result,  in  grid  and r e d p r i n t s .  a systematic a  regard to  u n c e r t a i n t i e s due  the reference  18.83 + 0.10 f o r t h e r e d p r i n t print.  (Bok  f o r the reference  reference  needed  e r r o r expected  f o r each of the b l u e  counts  were  large s t a t i s t i c a l  of s t a r s i n each square  square  four corners  prints  very  statistical  performed twice  the  here  i n o u r map. A l l c o u n t s were made w i t h  power  to  used  (1978). E n l a r g e d  blue  'reseau'  power  used  and  The d a t a  of  half  procedure  by Dickman red  counts.  T h e o r y , D a t a And R e s u l t s  of the care  is  the apparent  the four corners  was  m a g n i t u d e d e t e r m i n e d was  18.18 ± 0.25  for  the  blue  56  The with  number  adjacent  distribution  of  stars  values  counted i n each square was averaged  i n order  to  obtain  on  more  squares  used  had  immediate  very  neighbours.  smoothing  done  by  of  T h i s i s probably more a c c u r a t e than  j u s t a s s i g n i n g one s t a r over each region without any was  little  with one or more s t a r s . In r e g i o n s where no  s t a r s were counted a r e s u l t was o b t a i n e d from the the  uniform  c o n s i s t e n t with the r e s o l u t i o n of our CO contours.  The weighted average of the s t a r counts effect  a  stars,  as  Dickman (1978). The weighting f u n c t i o n used i s as  follows:  3. \ - > \  ,, V + S+a.r Co ant  0  w  . J , / f interest / '  3lcen+recL on + ne \ r • i \ ot m re.r e s t  The weighted s t a r counts f o r each used  to  determine  utilizing contain per  an  effective  t a b l e s compiled by  van  grid  element  extinction. Rhijn  square/ " '  are then  This  (1929).  was  These  done tables  smoothed values of the l o g a r i t h m of the number of s t a r s  square  magnitude,  degree, m,  and  brighter given  than  an  apparent  i n ten degree  steps  photographic of  galactic  l o n g i t u d e . The t a b l e a c t u a l l y used f o r t h i s work i s c o n t a i n e d i n Allen's "Astrophysical  Quantities".  Van R h i j n ' s t a b l e s have long been i n q u e s t i o n . C o n s i d e r a b l e c o r r e c t i o n s had t o be used to r e c o n c i l e the d i f f e r e n t systems  in  the s t a r  Unfortunately,  these  catalogues tables  used  remain  magnitude  in h i s compilations. the  only  source  of  57  information Van  for general  Rhijn's  photographic counted old  star  tables  give  p e r square  photographic  magnitude  i s very  prints  used  we s i m p l y  degrees.  as a f u n c t i o n of the o l d to  degree a t a s p e c i f i c  In r e d u c i n g  -9.0  log N  m a g n i t u d e . Here N r e f e r s  blue magnitudes.  of  counts.  the  number  galactic  of  stars  l o n g i t u d e . The  n e a r l y t h e same a s t h e modern  the blue  counts  the table adjusted  from  the  for a galactic  The i n t e r p o l a t e d r e s u l t s  from A l l e n  Palomar latitude  are given  i n T a b l e V. If  one c o u n t s  reference to these the  region, counts.  same  should  then,  one may a s s i g n a l i m i t i n g  I f a t some p o i n t  procedure  be l e s s  through  t h e number o f s t a r s p e r s q u a r e  the  A(pt)  than  then  m(ref). This  obscuring  we have t o f i n d  linearity  6  f t  the blue  in  f t  b^ = b . f i  exactly  plane.  2 K  one  fewer  stars  are  seen  i n the blue. f o r blue  f o r the  magnitudes  red print.  tabulations i s their Therefore,  we  can  An near  write  solution  f o r r e d magnitudes ( i . e .  one  can  order treat  t h e same manner a s t h e b l u e  m a g n i t u d e s we have  m(pt),  at that point i s  +...). To t h e f i r s t  Therefore,  repeats  magnitude,  (1978) c o n s i d e r s a s e r i e s  relationship  + b^m^ + c m  c ^ = 0 and  magnitudes For  6  m(ref),  The e x t i n c t i o n  approach  + b m . Dickman 6  means  t h e van R h i j n  corresponding  l o g N(m^) = a that  of  magnitude,  the cloud  tables are only v a l i d  similar  i n the  corresponding  magnitudes  c l o s e to the g a l a c t i c  fe  the  a  property  l o g N(m ) = a for  cloud.  = m ( r e f ) - m(pt)  S i n c e van R h i j n ' s  important  the  inside  degree  he f i n d s the red  magnitudes.  58  where b  ft  since  = 0.35 f r o m van R h i j n . F o r t h e r e d m a g n i t u d e s we  = b The  = 0.35.  ft  final  step  is  the  m a g n i t u d e s t o some s t a n d a r d to  take  All  converted  Reduction  V = 5500  and b l u e m a g n i t u d e s  'standard'  time.  The  A  are given  possible  s  4  3  6  discussed  0  5  v  r e l a t i n g red 1978).  0  0  A .  'standard'  (Dickman  suspect  are  extinction  A  0  for  A  quite  in  detail  was  features present  on t h e r e d and b l u e  well.  possible.  was d e t e r m i n e d f o r e a c h  intercomparison  fairly  wavelength.  extinctions,  «« "~  law h a s been  deviations  8  colour  some in  (1976).  Once t h e v i s u a l  agree  visual  factors  below  I  6  I.3LI A  reddening  Dickman's t h e s i s  two  It i s conventional  visual  l a w . The c o n v e r s i o n  to v i s u a l  0.1b  .  A  termed  the  e x t i n c t i o n s i s made by a s s u m i n g a  reddening  *  of  angstroms as the standard  to v i s u a l  A „  reduction  c o l o u r magnitude.  extinctions are  interstellar  The  have  The m a g n i t u d e  For  our  cloud  extinction  we  found  contour  of the red e x t i n c t i o n  colour,  maps  the to  disagrees  59  significantly  from  the  (A >, 3 . 5 ) . The v i s u a l became i n c r e a s i n g l y A  v  had  that  more  from  stars  the  per  red  large  from  extinctions  the  red  print  f o r the blue s t a r counts as S i n c e the r e d Palomar  grid  element  the  print  extinctions  f o r A >, 3.5 a r e p r o b a b l y  prints  of the t r u e v a l u e than  those  obtained  more  from  the  print.  counted  overall  uncertainty in A  i s p r o b a b l y no more t h a n  greater  extinction  several  magnitudes.  particularly  on  of more  distant  that  one  we e x p e c t  field  will  reference  magnitude.  limit  the e x t i n c t i o n s  no  stars  a r e a s o f t h e Palomar s h o u l d be r e c o n c i l e d  that we  were  found  per  o f f the g a l a c t i c  one s t a r  change t h e r a t i o region  and  From  extinction. a r e lower  the  element.  star  Since  between t h e number of s t a r s slight  limits  to  accurate were f o u n d  of the r e s u l t s  by t h e  element  feel  T a b l e VI g i v e s a summary  be  p l a n e and 800 p a r s e c s  I n c o n c l u s i o n , we  i n r e g i o n s where no s t a r s  can  f o r the presence  grid  per g r i d  t h e number  are  prints.  few f o r e g r o u n d s t a r s a s i n d i c a t e d  Subtracting  of  i s the expected  counted.  no e v i d e n c e  star  areas  t h e HII r e g i o n  since  by a s m a l l amount. T h i s l e a d s t o a  the a c t u a l  The  where t h e u n c e r t a i n t y i s  encompassing judge  foreground  222 i s l o c a t e d  counts.  except  problem  the blue p r i n t  than  Sharpless  region  to  of f o r e g r o u n d s t a r s  counts  star  The s q u a r e s  f o r r e g i o n s where s t a r s were  v  one  a lower  i n the exposed  A further number  are  difficult  distinguished  of  h i g h e r than  for  derived  on a v e r a g e  The  the  extinction  above 3.5 m a g n i t u d e s .  representative  the  only  increased  determined  blue  blue  of  blue  throughout stars  in  i n the obscured underestimate c o n f i d e n t that one  in a grid of t h i s  magnitude, element. chapter.  60  T a b l e V -Van The  Rhijn's  logarithm  Table  f o r b = -9.0"  of t h e number o f s t a r s of a l l m a g n i t u d e s p e r  square degree to a l i m i t i n g heading Allen's  log N . m  This  "Astrophysical  data  m a g n i t u d e , m,  is  i s interpolated  Quantities".  given  under  the  f o r b = -9.0°  from  61  Table m  log  V -Van N  m  Rhijn's Table  m  log  N  m  f o r b=-9.0°  m  log  12.0  1.63  14.4  2.62  16.8  3.49  12.1  1.67  14.5  2.66  16.9  3.52  12.2  1.71  14.6  2.70  17.0  3.56  12.3  1.76  14.7  2.74  17.1  3.59  12.4  1.80  14.8  2.78  17.2  3.63  12.5  1.84  14.9  2.82  17.3  3.66  12.6  1.88  15.0  2.86  17.4  3.70  12.7  1.92  15.1  2.89  17.5  3.73  12.8  1.97  15.2  2.93  17.6  3.77  12.9  2.01  15.3  2.96  17.7  3.80  13.0  2.05  15.4  3.00  17.8  3.84  13.1  2.09  15.5  3.03  17.9  3.87  13.2  2.13  15.6  3.07  18.0  3.90  13.3  2.17  15.7  3.10  18.1  3.94  13.4  2.21  15.8  3.14  18.2  3.98  13.5  2.26  15.9  3.17  18.3  4.01  13.6  2.30  16.0  3.21  18.4  4.05  13.7  2.34  16.1  3.. 24  18.5  4.09  13.8  2.38  16.2  3.28  18.6  4.13  13.9  2.42  16.3  3.31  18.7  4.17  14.0  2.46  16.4  3.35  18.8  4.20  14.1  2.50  16.6  3.38  18.9  4.24  14.2  2.54  16.7  3.42  19.0  4.28  14.3  2.58  16.8  3.45  N  m  Figures  11, 12, and 13 A ,  The  magnitudes  standard  procedure  Theory,  Data,  represent indicate  Palomar  of  outlined  the e x t i n c t i o n the r e s u l t s  figures  converted  conversion regions  procedure  represent  t h e Palomar  intervals  13  III.6-Star on  (B=4300  average  A)  contour  extinction  are  scaled  of  S  6 ( 1 9 5 0 ) = 35°13'00"0  (Right  (1978).  1.8  Ascension)  (Declination)  11 the  preceeding  (VS5500 A ) .  (0.0,0.0),  = 04 26 34. 0  would  the red p r i n t  the  in  map  Figure  The  o f t h e n e b u l o s i t y as seen  The a x i s  M  a 4  print  from of  the  Counting  F o r example,  i s o u t l i n e d i n Dickman  H  each  the r e s u l t s  the  the extent  using  3 and 4 magnitudes.  the blue  visual  the c e n t r e  0((1950)  extinction.  is  to  prints.  from  numbers  12 g i v e s  determined  section  i s between from  E x t i n c t i o n Contours  were  in  The of  Figure  ( R = 6500 A) and F i g u r e  v  extinction  interval  Survey.  and A  R  and R e s u l t s .  the  represents  of  A ,  6  The  dashed on  each  arcminute  Figure  11 -A  6  Extinction  Contours  Figure  13 -A„ E x t i n c t i o n  Contours  G6  T a b l e VI - D a t a Column  Summary  1  (x.x,y.y)  gives  means  the  x.x  arcminutes d e c l i n a t i o n  coordinates  arcminutes  right  from our nominal  (XO950) = 0 4 2 6 3 4 f u ( R i g h t H  M  8 (1950) = 35°13'oo'.'o  Column  2 i s t h e o b s e r v e d peak  column  3  Column and  gives 4  gives  6 give  density, fully  the  1 2  CO 1 3  temperature 1 3  CO  N  1 3  opacity (X10  1 4  CO  profile  ( K ) . The (nepers) and  ascension  i n chapterI I I .  and  y.y  Ascension)  L.S.R.  temperature velocity  temperature half  last the  widths two  generated  (K) and (km s ~ ) . 1  ( K ) . Columns 5 (km s " ) 1  columns  c m ' ) . A l l of the c a l c u l a t i o n s 2  observation.  centre,  radiation  excitation  CO  each  (Declination)  corresponding  the expected  radiation expected  the  1 2  of  1 3  CO  give  and the  column  are described  Table VI -Data Summary mi  (0.0,-14.4)  8.5  -1.0  11.9  1.9  1.2  0.15  27  (0.0,-12.6)  14.1  -0.9  17.6  2.1  3.0  0.23  89  (-10.8,-10.8)  12.8  -2.5  16.3  1.9  2.6  0.22  67  (-9.0,-10.8)  14.1  -1.3  17.5  2.2  2.9  0.23  93  (-5.4,-10.8)  14.6  -1.8  18.1  2.5  3.1  0.24  120  (-1.8,-10.8)  17.1  -2.0  20.6  2.6  4.3  0.29  190  (1.8,-10.8)  13.3  -1.1  16.7  2.5  2.8  0.24  99  (5.4,-10.8)  17.2  -0.6  20.7  2.4  4.3  .0.29  170  (7.2,-10.8)  20.8  -0.7  24.3  2.4  6.3  0.36  290  (9.0,-10.8)  14.2  -0.7  17.6  3.5  3.0  0.24  160  (10.8,-10.8)  11.5  -1.6  14.9  2.2  2.3  0.22  69  (-9.0,-9.0)  11.5  -1.5  14.9  2.6  2.3  0.22  80  (0.0,-9.0)  15.9  -1.2  19.4  2.3  3.7  0.27  130  (9.0,-9.0)  14.8  -1.0  18.3  2.0  3.2  0.24  97  (-7.2,-7.2)  10.4  -1.5  13.8  2.1  1.9  0.20  49  (0.0,-7.2)  17.5  -1.3  21.0  1.6  4.4  0.29  120  (3.6,-7.2)  14.2  -2.4  17.6  3.1  3.0  0.24  140  (5.4,-7.2)  15.9  -1.4  19.4  2.7  3.7  0.27  160  (7.2,-7.2)  15.4  -1.0  18.8  2.9  3.4  0.25  150  (9.0,-7.2)  14.8  -1.6  18.3  2.5  3.2  0.24  120  (-5.4,-5.4)  10.1  -1.5  13.5  2.0  1.8  0.20  46  (0.0,-5.4)  13.6  -1.0  17.1  2.3  2.8  0.23  95  (3.6,-5.4)  18.9  -1.0  22.4  2.1  5.3  0.33  190  (5.4,-5.4)  13.9  -1.1  17.4  2.8  3.0  0.25  120  2  A  V  rn  ml J A,  Position  1 2  ex  AV  1 3  1  L  1  1  N  1  3  P o s i t ion  rni  2  A  V  m i  e*  !  AV  1  3  rp 1 1  3  A  /£. 1 3  N  X  (7.2,-5.4)  20.9  -1.0  24.3  1.7  6.3  0.36  210  (9.0,-5.4)  13.1  -1.3  16.5  2.0  2.8  0.24  78  (-9.0,-3.6)  12.5  -2.5  15.9  1.8  2.5  0.22  63  (-3.6,-3.6)  11.8  -1.9  15.2  1.9  2.3  0.22  54  (0.0,-3.6)  15.2  -0.9  18.6  2.3  3.4  0.25  120  (3.6,-3.6)  11.3  -2.0  14.7  2.8  2.2  0.22  82  (5.4,-3.6)  13.5  -1.4  16.9  2.2  2.9  0.24  91  (7.2,-3.6) Bad P o i n t (9.0,-3.6)  c.12.0  -1.5  15.4  2.4  2.4  0.22  77  12.2  -1.6  15.6  2.0  2.4  0.22  67  (10.8,-3.6)  12.6  -1.6  16.0  1.7  2.5  0.22  59  (-9.0,-1.8)  11.5  -1.8  15.0  1.6  2.2  0.21  47  (-1.8,-1.8)  10.5  -2.1  13.9  2.2  2.0  0.21  54  (0.0,-1.8)  17.2  -1.3  20.7  2.1  4.2  0.28  150  (1.8,-1.8)  8.2  -1.1  11.5  1.4  1.5  0.20  25  (3.6,-1.8)  12.0  -2.1  15.4  2.1  2.4  0.22  68  (5.4,-1.8)  13.8  -1.0  17.2  2.4  3.0  0.25  110  (7.2,-1.8)  13.1  -1.2  16.5  2.4  2.8  0.24  95  (9.0,-1.8)  15.8  -1.0  19.2  2.1  3.7  0.27  120  (-12.6,0.0)  10.0  -0.6  13.4  1.0  1.8  0.20  23  (-10.8,0.0)  7.7  -1.8  11.1  1.6  1.3  0.19  25  (-9.0,0.0)  11.1  -3.5  14.5  1.6  2.2  0.22  46  (-7.2,0.0)  12.7  -2.1  16.2  2.3  2.7  •0.23  85  (-5.4,0.0)  2.9  -1.3  6.1  1.0  0.5  0.19  6  (-3.6,0.0)  14.5  -1.9  18.0  1.8  3.1  0.24  81  (-1.8,0.0)  8.6  -2.3  11.9  2.5  1.6  0.20  46  (0.0,0.0)  9.9  -2.1  13.3  2.3  1.9  0.22  55  3  Position  mi 2 1  A  V  mi 2 1  ex  AV  1 3  m i 3 1  A  ^-1 3  N  1 3  (1.8,0.0)  14.0  -1.9  17.5  2.4  2.9  0.23  100  (3.6,0.0)  12.3  -0.5  15.7  2.1  2.5  0.22  70  (5.4,0.0)  11.1  -2.2  14.5  2.5  2.2  0.22  72  (7.2,0.0)  11.3  -1.1  14.8  2.8  2.2  0.22  84  (9.0,0.0)  12.8  -0.8  16.2  2.4  2.6  0.23  85  (10.8,0.0)  11.0  -2.5  14.4  2.2  2.1  0.21  59  (12.6,0.0)  7.4  -0.9  10.8  2.3  1.2  0.18  31  (-1.8,1.8)  9.6  -1.3  13.0  2.8  1.8  0.21  63  (0.0,1.8)  7.6  -1.0  11.0  1.5  1.3  0.19  23  (1.8,1.8)  9.6  -1.7  13.0  2.0  1.8  0.20  43  11.0  -2.1  14.4  2.1  2.1  0.22  59  (0.0,3.6)  7.5  -1.7  10.8  2.0 . 1.3  0.19  30  (3.6,3.6)  9.6  -2.2  13.0  1.7  1.8  0.21  37  (5.4,3.6)  10.1  -1.1  13.5  1.9  2.0  0.22  46  (7.2,3.6)  13.7  -0.2  17.1  1.1  2.9  0.24  44  (-9.0,5.4)  12.4  -1.2  15.8  1.7  2.5  0.23  58  (-5.4,5.4)  13.2  -0.9  16.6  2.0  2.8  0.23  77  (-1.8,5.4)  11.4  -1.4  14.8  1.4  2.3  0.22  44  (0.0,5.4)  9.7  -1.3  13.1  2.2  1.8  0.21  49  (1.8,5.4)  5.6  -1.1  8.9  1.5  0.9  0.17  15  (5.4,5.4)  11.1  -1.7  14.5  1.7  2.2  0.22  50  (9.0,5.4)  13.0  -1.0  16.4  2.0  2.7  0.23  75  (-7.2,7.2)  12.0  -2.0  15.4  1.7  2.4  0.23  55  (0.0,7.2)  15.1  -1.1  18.6  1.4  3.3  0.25  68  (5.4,7.2)  13.9  -1.4  17.4  1.7  2.9  0.23  74  (7.2,7.2)  13.1  -2.3  16.5  1.8  2.7  0.23  69  (-3.6,3.6)  Position  rp 1 2 A  rp l 2 ex  (-9.0,9.0)  6.4  -1.5  9.8  (0.0,9.0)  11.6  -1.2  (9.0,9.0)  13.2  (-10.8,10.8)  rp l 3 A  3  1.5  0.9  0.15  14  15.1  2.0  2.3  0.22  63  -1.9  16.. 7  2.2  2.7  0.23  84  5.4  -2.1  8.7  1.2  0.7  0.15  9  (-9.0,10.8)  7.8  -1.1  11.2  1.0  1.1  0.16  13  (-5.4,10.8)  10.0  -0.6  13.4  1.9  1.7  0.18  39  (-1.8,10.8)  10.6  -2.0  14.0  1.2  1.9  0.20  30  (0.0,10.8)  9.5  -2.1  12.9  2.5  1.6  0.18  48  (1.8,10.8)  • 7.6  -0.9  11.0  2.0  1.1  0.16  26  (7.2,10.8)  8.5  -0.8  11.9  1.6  1.4  0.17  25  (9.0,10.8)  13.3  -1.2  16.7  2.2  2.7  0.23  84  (0.0,12.6)  5.6  -1.2  8.9  1.7  0.7  0.14  14  1  V  AV  1 3  N  1 3  71  IV. IV.1.1-Previous  a s NGC  (1917)  location object five.  was  of s i z e Herbig  HCV101  1579  given.  Introduction  Perseus.  Hubble  A general  c a t a g o r i z e d NGC  (1922)  suggested  (1956)  f o r NGC  i s 1 7 . Herbig  Lk H O U 0 1  1 5 7 9 . The noted  that  Hubble's  relation  the  exciting  star  explained material The regions  as  superimposed  222  a  small  bright  nebula,  crossed  I t l i e s 'on t h e edge o f a v e r y  d e s c r i b e d by t h e ' B l i s t e r '  t o i n t h e INTRODUCTION),  formation  i s fairly  Sharpless  222: t h e e x c i t i n g  the molecular  resolving  Model  only  that  He  by  of the  correctly l a n e s of  Lk  HCX101.  from  a  list  i s also  of  of nine  given  of dark  In  to  source of  star,  of the r e g i o n  a s an  magnitude  this  bright irregular  The l o c a t i o n  the  one  magnitude  result  (1959).  2 2 2 i s d e s c r i b e d as a very  Sky S u r v e y p r i n t s  from  nebula.  derived  S. S h a r p l e s s  Palomar  referred  and  is  s i x arcminutes.  a  the  was  and  apparent  on t h e i l l u m i n a t i n g  name S h a r p l e s s by  of  problem  diameter  lanes. As  this  compiled  Sharpless with  that  dimensions  and  i s a discrepancy  brightness  and  size  photographic  there  by F.G.  1579  as the probable  m a g n i t u d e s between t h e o b s e r v e d connecting  first  description  two on a s c a l e i n c r e a s i n g i n  illumination Lk  Observations:  2 2 2 a p p e a r s t o h a v e been o b s e r v e d  Sharpless Pease  DISCUSSION OF RESULTS  of  HII  catalogue HII r e g i o n  given.  show S h a r p l e s s  222  by s e v e r a l o b s c u r i n g  dark  l o n g and narrow dust  lane.  (Israel  1978:  this  1977, G i l m o r e  configuration  of  star  common. T h e r e a r e f o u r components p r e s e n t i n star,  t h e HII r e g i o n , t h e HI r e g i o n ,  c l o u d and o u r s p a t i a l the  latter  two.  resolution  The f i r s t  i s capable of  two components a r e  72  treated  briefly  The a  spectral  matter  object  of  sequence Altenhoff  type  star  Panagia  The has  a  at least  spectral  of  of the spectrum  1977).  The  1977)  A  = 10 m a g n i t u d e s . F o r  determine  a mass l o s s  the v i s u a l  of  extinction.  of the  consistent  w i t h a B0.5 s t a r .  surrounding nebula  source appears  (1970)  IRC 40091  star  is  Cohen  to  a NGC  be  bright  Lk HCX101  three  = 17  p3  and t h e there  present.  f o r Lk HGX101 above  5  GHz  1980) w i t h  some  30 and 90 GHz  (Schwartz  and  1  i s continuous  (Cohen and  P (3  (Thompson  lines  1979), Cohen  source  M  &  yr ~  Cohen  (1980) u s e s In each  case  between  9  infrared  finds  (1980)  also  and  several  10  source  with  the t o t a l magnitudes  exciting  1971).  well  methods t o  he f i n d s and  coincident  (Grasdalen  (1980)  which c o r r e s p o n d s  1  (Neugebauer a n d L e i g h t o n  t o be near  m  g i v e n by  1971) i n d i c a t e s  1579 (Cohen a n d Woolf  found  et a l .  (S/* V ,"Cohen  point - 5  Brown  parameters  extinction  spectrum  3x10  extinction  Lk HCX101  the  (Herbig  (Cohen and K u h i  a B0.5 Z.A.M.S. s t a r .  Dewhirst  to  between  the  have  o f a z e r o age  1973,  the r a t i o of hydrogen H/  that  data  1976), where a Z.A.M.S. BO.5  source  optical  al.  calculates  to  t e n y e a r s most  magnitude of  one  been  (1956) c l a s s i f i e d t h e  (Allen  800 p a r s e c s  index  Lk H0O01, h a s  i s probably  according  of t h e p o i n t  1979) and from  with  type  e t a l . 1976, H a r r i s  et v  In t h e l a s t  The p h o t o g r a p h i c  star,  Herbig  t e n magnitudes of v i s u a l  flattening  Kuhi  since  (Z.A.M.S.) BO.5 s t a r  spectrum  Spencer  star.  i s defined  of  nearly  ever  the s p e c t r a l  (1973).  distance  section. of t h e e x c i t i n g  debate  that  1976,  are  type  a s an F t y p e  indicated main  in this  Cohen  the and  the i n f r a r e d  1969). The K m a g n i t u d e Gaustad  1971,  Allen  73  1973,  Strecker  magnitudes  and Ney  (Cohen and  excess  and  rich  both  gas  and  a  Dewhirst  emission dust  print  Photographic  Sky S u r v e y  these, a  1970).  line  envelope  unpublished  molecular  1974) w i t h a c o l o u r  of  the  of t h e i r  observations. infrared Lk  Figure  a  mass In  HCX101 c a n t h u s  3 x 10~ infall  M<2>  5  1980). The d u s t  producing present.  _  1  it  Cohen  and any  coincidence  in  the  with  the  CO  of the Steward  Observatory  a s a BO.5  i n an e a r l y  . The e v i d e n c e  has  the  I t appears  shell high  is  a l . 1976, Thompson and Reed cent  a weakly  this  t h e HII  most  at  a  ionized  thick  of than  collapsing.  reached  t h e main  circumstellar  (Simon and Dyck 1977,  likely  responsible  at  the  1976). The s h e l l ionizing  The  i s about  a t 800 p a r s e c s , O s t e r b r o o k  ionized  rather  and t h e i n f r a r e d  region  halo.  shell  a  rate  for  excesses  and HII r e g i o n s a r e clumped i n  of the s t e l l a r  circumstellar  star  recently  reddening  et  creating  mass  Lk Hon 01  that the dust  way w i t h  per  very  around  asymmetric  two  star  of mass l o s s  o f t h e mass l o s s ,  formed  both  has  an  inner  stars  i m p l i e s t h a t t h e p r o t o s t a r i s no l o n g e r  shell  an  Near I n f r a r e d  of o b s e r v a t i o n s . Table VII g i v e s  be r e p r e s e n t e d  y r  dust  B0.5  an  print.  s e q u e n c e . As a r e s u l t  from  On  a 2.5 m a g n i t u d e c o l o u r e x c e s s . Of  14 i s a d i a g r a m  a l l probability  only  Lk Hon 01.  dozen  p h a s e o f e v o l u t i o n . I t seems t o be l o s i n g about  infrared  provides evidence f o r  Observatory  t h e r e a r e about  positions  I - K o f 5.72  observed  surrounding  t e n a r e w i t h i n our f i e l d  summary  The  spectrum  Steward  cloud with at l e a s t  index  total  core  (Thompson  geometry  photons t o extinction  permits escape, arising  9 t o 10 m a g n i t u d e s . F o r a (1974, T a b l e  r e g i o n o f 0.7 a r c s e c o n d s  and  a  2.3) more  suggests extended  74  zone  of  well  emission  with the  (1974)  (32 a r c s e c o n d s ) . These r a d i i  observed  estimated  Altenhoff inner  the  inner  e t a l . (1976) and  core  existence (1976)  radio  size  to  picture.  0.5  the size  (1976)  emission  GHz d a t a . The q u e s t i o n o f t h e asymmetry solved  by  assuming  (1971) s u g g e s t e d elliptical suggests  this  stellar  by  the  circumstellar  distribution,  the  polar  radiation.  thinnest  caps.  youth  the e a r l y  high  mass  candidate  over  with which  et a l .  can  in  be  Herbig  fact  be  Cohen  (1980)  lies  in  a  t h e p o l e s o f Lk HOM01. In flux  can  escape  t o be t h e c a s e w i t h t h e the o p t i c a l  nebula,  halo.  type, the h i g h  observed.  actually  helps maintain  radio  notes the  nebula  might  of the s t e l l a r  of the i l l u m i n a t i n g  spectral loss  dust  the  on t h e 5 and 10.7  the  nebula  T h i s appears  This flux  1579, and t h e o b s e r v e d The  further  HII r e g i o n i s f l a t t e n e d .  the a s s o c i a t e d  way o n l y a s m a l l f r a c t i o n  through  NGC  the  narrowed  i n shape and have t h r e e p a r t s o b s c u r e d . that  flattened  that  that  Schwartz  Altenhoff  based of  fairly  one a r c s e c o n d .  both  and  as 35 a r c s e c o n d s  and  than  arcseconds. Harris  o f t h e more e x t e n d e d  gives  Spencer  c o r e was l e s s Harris  do a g r e e  star,  Lk H&101,  i s supported  infrared  excesses  Lk Hon 01 a p p e a r s  t o be an  s t r o n g CO e m i s s i o n w i l l  and  the  excellent  be a s s o c i a t e d .  75  Infrared  Star  A, CO ext i n c . c o n t o u r s (mag.) (kelvin) 1 3  1 3  C 0 L  1 5  2  10.0  0.8  2.8  8.0  #2-(5.7,-13.1)  10.0  2.2  2.3  6.0  #3-(-2.7,-6.6)  8.5  2.2  2.8  6.0  #4-(-7.0,1.6)  14.0  2.0  3.3  12.5  #5-(-3.0,6.7)  9.0  1.9  2.8  6.0  #6-(2.2,-1.8)  5.0  1.5  1.8  4.0  #7-(3.8,-4.5)  13.0  1.8  4.5  14.0  #8-(3.5,-4.2)  12.0  1.7  4.0  11.0  #9-(4.1,-3.5)  11.5  1.6  2.8  10.0  #10-(4.9,-3.1)  12.5  1.6  2.8  9.0  #ll-(5.6,-3.8)  12.5  2.0  2.8  10.0  The  eleven  the c e n t r e  Star  Positions  infrared  stars  are l i s t e d  o f our o b s e r v a t i o n  CV(1950) = 0 4 2 6 3 4 . 0 H  n  S  given  are  extinction, generated positions.  1 3  the  expected CO  1 2  CO 1 3  CO  column d e n s i t y  Very  little  (Right  positions  Ascension)  (Declination)  radiation  temperatures,  radiation  temperatures,  for  of  each  coincidence  CO h o t s p o t s and t h e i n f r a r e d  with t h e i r  field.  £ ( 1 9 5 0 ) = 35°13'00['0  Also  N ( C0) contours (xlO cm )  #1-(13.4,5.5)  Table VII - I n f r a r e d  from  C0 contours (kelvin) 1 2  stars  between c a n be  the  visual and  infrared  the p o s i t i o n s seen.  the star  of the  76  Figure  14  -Infrared  Figure  14  Diagram  is  a  schematic  representation  of  the  infrared  o  print Dr.  (8000 t o  E.  Craine  indicates  the  9000 of  the  centre  A)  reproduced  of  our  M  survey  (Right  M  our  i s i n d i c a t e d by  observation  summarized the  field  in Table  f i g u r e i s 7.03  LH101 are  and  the  Star  m i l l i m e t r e s per  converging  from arrows  Ascension)  (Declination)  other  numbered.  VII-Infrared  permission  field,  6 ( 1 9 5 0 ) = 35 °13'00!'0  H0U01  kind  S t e w a r d O b s e r v a t o r y . The  0(0950) = 0 4 2 6 3 4 f o  Lk  by  1.8  The  infrared details  Positions. arcminute  The  of  stars  in  each  are  scale  of  interval.  77  F i g u r e 14 - I n f r a r e d Diagram  /  /  / 6 9 '  I  /  \ \  I  78  IV. 1 . 2-Previou,s The  Observations:  first  twenty-one c e n t i m e t e r  obtained  by  coincides  e x a c t l y with  velocity  Riegel  incomplete  Churchwell  precisely given  1  of  He  data  of S h a r p l e s s  detected  map  of  HI  found  one k e l v i n .  a  systematic  was  obtained  maximum  main  by  radial  Felli  beam  _  1  .  and  brightness  The peak HI t e m p e r a t u r e was l o c a t e d  coordinates.  The p a r t i a l l y  sampled  map  i n F i g u r e 15. most  c o m p l e t e HI d a t a  ( 1 9 8 1 ) . An example  yet obtained  16.  The d a t a  the  Dominion Radio A s t r o p h y s i c a l O b s e r v a t o r y ,  were o b t a i n e d  C o l u m b i a . The s p e c t r a the  absorption  the  observed  absorption  in  component  using  1 2  i s present  structure outside  Figure The  front  of  Lk H0r*lO1  17 i s a t h r e e  face  1  Penticton,  , c o i n c i d e s very  profiles  (Figure  right  faces ascension  used  well 18).  spectra  we  see  no  evidence  profile.  dimensional  d i s p l a y of t h e i r  of the highest  indicate  the  HI  the  The  i s similar  HI  of  data.  position  i s l o c a t e d about contour  HI v e l o c i t y  or d e c l i n a t i o n .  at Penticton  with  i n a l l t h e s p e c t r a p r o v i d e d by  the c e n t r a l  to the east  British  i n H I . The v e l o c i t y o f  i n d i c a t e d . As we c a n s e e Lk HO<101  other  resolution  _  in Figure  interferometer at  i s a map o f t h e i n t e g r a t e d HI w i t h  arcminutes two  CO  i s given  the s y n t h e s i s  0 ± 2 km s  our  i s t h a t o f Dewdney  spectra  show two components  component, dip  of t h e i r  Dewdney a n d R o g e r . From t h e s e  constant  which  w i d t h o f 8.1 km s  half  Roger  The  an HI f e a t u r e  and a v e l o c i t y  and  three  were  a  at the o p t i c a l  The  velocity  222  Lk HCX101. He f o u n d  ( 1 9 7 2 ) . They  temperature  is  (1967).  o f 3.5 km s ~  An  HI R e s u l t s  Note t h a t t o our  1 2  centre.  structure for the  spatial  C0 resolution  79  for  Sharpless  given  222.  in section  A  full  IV.2.  comparison  of  the  two  data  sets  is  80  Figure  15 -HI  This  HI  incomplete optical The  C o n t o u r Map, contour  s u r v e y by F e l l i  coordinates  contour  temperature  map  interval o f one  Felli  kelvin.  Churchwell  of S h a r p l e s s 222 and  coincide. is  and  0.2  Churchwell  i s the  ( 1 9 7 2 ) . The  This i s indicated K  giving  result  a  peak  as  o f an  radio the  and  cross.  brightness  81  '  1  20  Figure  16 -HI  This  spectra  is  components the  measured  figure  0  -10  1  Dewdney and Roger  (1981)  HI p r o f i l e  shows t h e two component  that  of  Lk H&101  result  s p e c t r u m . The  in  heavy  residual  from Dewdney and Roger spectral  (5.4,-3.6).  i n e m i s s i o n and a b s o r p t i o n fitted  -20  V(km-sec" )  i s a representative  ( 1 9 8 1 ) . The  and  Profile,  10  a r e shown lines  The  fits.  individual  in light  superimposed  i s shown b e l o w .  This  lines, on t h e  82  4*27"  4*26  Right  Figure  17 -3-D  This  is  emission  Synopsis a  show HI e m i s s i o n km s cm  - 2  _  1  .  column  continuum (white  star).  millijansky.  The  (DEC)  1981).  over  ranges  representation  Sharpless  showing the s o u r c e  synthesized  are beam  a r e f o r epoch  the f u l l  right  displayed  on  range  to intervals  Superimposed  levels  of  222. The shaded  the v e l o c i t y  steps correspond  Contour  corner. Coordinates integrated  with  density.  emission  results  dimensional  i n t e g r a t e d over  The c o n t o u r  in  o f t h e HI  three  association  m  Ascension  is  a  70,  i s shown  ascension the f r o n t  HI  contours to  +10  o f 1.5 x  10 °  contour  2  map  of  a s s o c i a t e d w i t h Lk H£X101  20,  1950.  -6  the  120  and  i n t h e lower  170 right  The s i d e p r o j e c t i o n s a r e (RA) face.  and  declination  (Dewdney and Roger  83  IV.1.3-Previous As be  we  Observations:  have  a young and  molecular ongoing  very  emission star  a r o u n d Lk  luminous and  t o be  no OH  (1973).  Only  The  antenna  velocity The Knapp  first  was  was  was  Two  c e n t r e on the  the  +12  s  of  away  region  in  of  also  C0  extended  0 ± 2 - 1  1 2  et a l .  an  s  the  km  s  - 1  .  . The  peak  noted  the  profile.  The  12  were a l s o  estimate  CO  was  done  observed small  t h a t about (1976)  velocity  f e a t u r e s as  seven  work.  distributed further  13  section  Knapp's  nothing  in  by CO. of of  Their  those  of  structure did  is  said  about  (1976).  with a from  of  1979).  found  They  with  irregularly and  the  Wilson  7 ± 2 km  to only a very We  other  .  - 1  222  1 of Knapp e t a l . ( 1 976)  brightest  proceeds  km  extended  treatment  Knapp e t a l .  the  extent  This  They  K.  positions  Hon 01.  same  et a l . (1973).  allow analytic by  Lk  Lada by  velocity  0.3  to  regions  detected  and  taken.  of S h a r p l e s s  (1976).  show  ±  with  i n t h e wings of t h e i r  f e a t u r e was  survey  been  rather large, 1.5  along  expects  detected  with a c e n t r a l  appears  emission.  Blitz  was  H&101  indicates  have  first  emission  spectra cover  Figure as  222  width  CO  of t h i s  survey  Wilson  it  12  et a l .  spectra  not  of  emission,  of CO  1971,  region studied corresponds  our our  half  masers  spectrum  temperature  presence  The  one  (2 a r c m i n u t e s )  profile  source  (Turner  in Sharpless  CO  Lk  a c o n s e q u e n c e one  a good a  emission  source  star.  IV. 1 .1  masers, g e n e r a l l y  or H O  vicinity  Results  in section  f o r m a t i o n . As  Hon 01  To d a t e Lk H6X101  indicated  CO  significant  this  shows t h e Lk  HLX101  profile  temperature  drop  as  c e n t r e . The  velocity  of  the  one  profiles  84  shown i n F i g u r e is  representative  profiles dip  of  Figure  for  of  show a d i s t i n c t  to self  that  et  2 i s approximately  absorption.  the  dust  d i p a t 0 km  Section (1976), n o t i n g  IV.2  s  crossing  _ 1  i n the  1 2  C0  compares  .  - 1  the s e l f  . This  velocity  Several  of  their  attribute  this  They  of t h e d i p s  the face  of our s p e c t r a that  s  profiles.  The d i s t r i b u t i o n  a l . (1976) a l s o c l a i m the sharp drop  ± 1 km  a l l of t h e i r  lanes  18 i s an example  -1  agrees  with  of S h a r p l e s s  222.  showing  the  absorption  dip.  Knapp  i s responsible  r a d i a t i o n temperatures. our  data  to that  of Knapp e t a l .  t h e many d i f f e r e n c e s a s w e l l as t h e  similarities.  85  F i g u r e 18 - C 0  Profile  1J  This  figure  is  Dip representative  e x h i b i t i n g the prominent d i p i n the 30 per  c e n t of our p o s i t i o n s  These  positions  appeared  of  12  C0  profiles  s p e c t r a l l i n e . Approximately  i n d i c a t e d the presence of t h i s to  be randomly o r i e n t e d  appear t o be r e l a t e d t o dark l a n e s .  and  and  the s p e c t r a l p o s i t i o n s are  could  do a p r o p e r v e l o c i t y a n a l y s i s .  dip.  did  S i n c e the d i p s are not  resolved not  the  not well  randomly d i s t r i b u t e d  we  86  IV.2-0ur Of  Observations the  f o u r components o u t l i n e d  have  covered  early  type  region. is  the  star,  From  less  than  one  area  section  covers  of  fainter the  of t h e  (1981) HI  data are  cross.  All  photograph the is  The  given  Lk  HC*101 a p p e a r s  a  small  o b s e r v a t i o n s the Surrounding  emission  of  of  this  red  stars  be  indicated.  A  prints  nebula  full  show an  NGC  1579.  exciting  on  This  components. They  print.  Plastic  t h e back  is  The  star,  central  arcminutes  six  from  the c e n t r e surrounds  arcminutes is  embedded  three degrees.  elongated  The  arcseconds.  Roger's  jacket  of  with  a  indicated same s c a l e with  discussion  five  analysis  region  Dewdney and  positioned  approximately  extent  and  overlay  may  HII  r e g i o n i s a more  Palomar  t h e o v e r l a y s a r e drawn t o t h e 19 and  an  cloud.  project  each  o f t h e HII  larger  i n the envelope  c e n t r e of  t o be  associated  t h e HII  two  we  the of t h e  as  the  aid  of  results  below.  the  region  size  r a d i u s 32  of t h e  enlarged  located  in Figure  Palomar by  with  the molecular  results  of  four guide  BO.5,  details  19 shows an  thesis.  in d e t a i l .  arcsecond.  overlays  the  radio  c l o u d and  Figure  two  probably  the  extended  a r e t h e HI  first  i n the p r e v i o u s s e c t i o n  molecular indicates  maximum  the  c l o u d i s about 'pockets'  ratio  the  surrounded nebula  emission  to  nebula.  The  l o n g o b s c u r i n g c l o u d of  average  extinction  HCX101,  bright  across. Fainter  a very  The  small  visual  magnitudes. Using  in  Lk  visual two of  extinction  is about HII  angular of  this  magnitudes. A star  count  strong v i s u a l  measured  is  of H atoms t o v i s u a l  at  extinction. least  extinction,  five A , v  87  from  B o h l i n e t al»  column 10 x  density  10  4 x  results  v  densities  f o r each  The  would  10 '  derived  at  extinction  magnitudes  obtained  agreement w i t h our the  star  Our km  s~  and  12  too  CO  exactly  with  (1973).  width  that  found  is  also  thirty  dip  in  by  their  spectra  result  of  the  two  velocity  and  suggest  the  to  section  CO  column  Bohlin  range  et a l .  from .8 t o  15  t h e v a l u e of (1981) but  visual  on  and  a  line  s~ .  star  count  11  not  extinction  velocity  The  1  for  cent  Our  the  profiles  in  from  analysis  of  our  this of  the  12  CO  this  CO  d i p and  so a n a l y s i s  evidence  is  not  for different  self-absorption  as  in  the cause  a  18).  two  of  lanes  there  of dark  spectra  velocity  is  dark  find  q u i t e randomly  possible.  in  In  the d i p i s the  the presence  of t h e  width.  (Figure  1  dip  We  et a l .  there  s"  emission  sharper  Wilson half  claim that  f a c e o f S h a r p l e s s 222. 12  are  -1.25  corresponds  profiles  c e n t r e a t 0 km  b a s i s they  of  velocity  velocity  t h e p r e s e n c e -of  components no  CO  Roger  from  profile.  d i p s are d i s t r i b u t e d  positions  (1981) f o u n d  and  of t h e  profile  between t h e  These p r o f i l e spectral  and  a c r o s s the  correlation  13  13  Knapp e t a l . (1976) and  per  self-absorption  cut  the  agreement w i t h  2 km  true  Knapp e t a l . (1976) n o t e  that  of  a gaussian  approximately distinct  1978,  extinctions  than  This  this  up  low.  a half  narrower  of  (Dickman  observations indicate  with  1  The  end  hydrogen  'pockets'  generated  Dewdney  calculations  counts.  are probably  by  with  - 2  the  from  magnitudes. T h i s i s i n e x c e l l e n t  a mean t o t a l  the  from  of t h e c l o u d s  visual  infer  atoms c m  2  Table VIII  2  h  1978).  of  atoms cm" .  2 1  lists  (1978) one  i s no  lanes.  throughout in  our  terms  of  Dewdney and  Roger  components  i n HI  f o r the p r o f i l e  dips.  88  A s t r o n o m e r s o f t e n make s i m p l i f y i n g determining without  adequate  justification.  (non  method, shows t h a t different  L.T.E.  Hobbs  decrease  (1981) the dips  assumed and  from  A  non  from  Bernes'  not f i n e  dips  conditions  Shuter  find  often  consequence  at the cloud  pronounced  noise  the  edge o f t h e c l o u d  edge a r e p r e d i c t e d the  and  real Our  rms an  peak  2.5  We a l s o  present,  be a b l e  find  the  say t h i s  i sa  these dips find  may  a few p r o f i l e s on dips  program  at the  km s ~  CO  radiation  1  cloud  geometry  is still  i n the better noise  dips. was 20 ± 2 K. Our s i g n a l and t e n f o r s p e c t r a  The v e l o c i t y h a l f w i d t h  1.5  just  t o d i s t i n g u i s h between  a v e r a g e d between e i g h t  to  that centre  With b e t t e r v e l o c i t y r e s o l u t i o n and  such as these  signal.  do  a more c o m p l i c a t e d  the  r a d i a t i o n temperature  ratio  observed  At  We  but cannot  since  models w i t h  dips  Our v e l o c i t y r e s o l u t i o n  have d i p s . P r o f i l e  one s h o u l d  features  noise  from  stage.  to noise  that  using  cloud.  developmental signal  centres  on t o p o f t h e p r o f i l e s .  Carlo  a t the cloud  conclusion.  on non L . T . E . c o n d i t i o n s  be  Monte  a r e a consequence of  a maximum d i p i n t h e p r o f i l e  this  developed  o f non L . T . E . a s o p p o s e d t o  (1981)  enough t o s u p p o r t  more  within  in  thermodynamic  (1979)  i n the p r o f i l e s  t o no d i p a t t h e o u t s k i r t s o f t h e c l o u d . is  local  L.T.E.) r a d i a t i v e t r a n s f e r p r o g r a m ,  Hobbs a n d S h u t e r  the  assumptions  e x c i t a t i o n t e m p e r a t u r e s a n d column d e n s i t i e s , o f t e n  equilibrium by  L.T.E.  towards  decreased  to with  slightly  t h e edge o f t h e o b s e r v a t i o n  field. The described  1 2  as  a  warm  temperature  background  distribution  (10 K) w i t h  can  be  a fragmented hot  89  cloud  southeast  are  o f Lk HO(101. S e v e r a l  located adjacent  velocity  h a l f width  density  calculation,  distinguished.  to the hot c l o u d  i s combined  This  regions  the  with  hot  (Figure  the T  and c o l d  i s illustrated  of c o o l  by  (  ft  1 2  N  (5  7 ) . When t h e C0) in  spots  the  gas  C O L  K)  1 2  C0  a  column  a r e more  clearly  (  1 3  CO)  contours  (Figure 10). The  generated  described as T  A  1 2  (  (Figure  CO) ratio  clearer on  the  since 1 3  (  AV(  1 3  1 2  13  CO)  the r a t i o  the  two  emission visual HCV101  1 2  of t h e T * ( A  CO hot spots.  1 2  CO) to  _( C0),  combines  1 3  of  Any  feature  i s not r e s o l v e d .  1 2  i s three  features  1 3  i n CO C 0 1  same  i n t h e C O c o n t o u r map a r e  the  well  i n s i d e a broad  i sa crucial  half  the c l a r i t y of width  resolved  region  of  1 2  CO,  fragments  of c o o l e r  and  molecular  away  d i f f e r e n c e between o u r r e s u l t s and t h o s e  (1976). from  with  Examination  Lk  N  distribution  (Figure 10).  emission  HOO01  nature  present  They  their  cold  of  the  regions  (-5.4,0.0),  A  v  CO  and at  latter  is  The  ,  drastic  indicate a general  located  i spartially  extinction,  1 2  a  temperature  (Lk HCX101). We do n o t o b s e r v e  s e v e r a l h o t and c o l d  (r.8,5.4). that  observe  centre  d e c l i n e . Our o b s e r v a t i o n s  peculiar  the  variation  others  Knapp e t a l .  decline  Lk  to  temperature  10) shows t h e  emphasizes  The n e t r e s u l t  There  CO  7 ) . Due the features  with  CO).  material  this  (Figure  CO column d e n s i t y ,  possibly  of  radiation  C O map b u t n o t p r e s e n t  The T*  CO  i n section III.4  CO  1 3  1 3  overlapped northwest  background  of  clumps. 1 3  CO  contours  Lk HodOl a  wider  by an  r e v e a l s two  (-5.4,0.0) region  area  of  and  of reduced decreased  o f t h e peak H I . The f o r m e r ,  i s a s i n g l e spectrum with  no d e t e c t e d  1 2  CO.  90  Surrounding supected  s p e c t r a have m o d e r a t e e m i s s i o n  t h a t t h i s might  However, t h e r e c e i v e r three  other  significant no no  1 2  1 2  1 2  be t h e r e s u l t  system appeared  profiles CO signal.  at this  the  position  CO emission  The  or a very star  i n a long c y l i n d r i c a l cool  counts  foreground  were  cloud  repeated  ("5.4,0.0) u s i n g a s m a l l e r r e s e a u a very  Either  through  grid.  the  no  integrated  and stars  1 2  the were  original  star  recorded  C O temperature  contours  around  o f Lk HCY101  this  smaller  Both velocity no  Wilson  evidence  is  any anomaly i n we have  required  (1973)  a n d Knapp e t a l . (1976)  forthis  s t r u c t u r e i n our r e s u l t s .  probably  precluded  seeing this of  profile. Our  structure.  the  spectrometer  r a n g e where a  found  temperature From Knapp  structure  quadratic  found  We  is  t o t h e n o i s e o f o u r s p e c t r a . The s t r u c t u r e i s a l s o  edge of. t h e  is a  t o map t h e r e g i o n .  a l . (1976) t h e peak t e m p e r a t u r e  close  was  et a l .  What  s t r u c t u r e i n t h e wings o f t h e c e n t r a l  resolution et  f e a t u r e as u n r e s o l v e d .  t e l e s c o p e beam w i d t h  The  do n o t show t h e p r e s e n c e of  (-5.4,0.0). C o n s e q u e n t l y ,  regard t h i s  CO  Palomar  position.  their to  our  From b o t h  (1981) do n o t f i n d  r e s u l t s a t Lk HOM01  evidence  of  t h e h o l e and Dewdney and Roger HI  entire  the emission.  i s slight  counts.  has  there i s  the  vicinity  There  showed  probably  i s absorbing  in  since  time  s m a l l o b s c u r i n g c l o u d below t h e r e s o l u t i o n  observations prints  hole  we  problems.  well  same  C O p r e s e n t . Two e x p l a n a t i o n s a r e p o s s i b l e .  cloud  of  of i n s t r u m e n t a l t o be w o r k i n g  collected Therefore,  present. At f i r s t ,  very  on t h e  baseline f i t  made. The  support  T* ( the  1 3  C O ) and  findings  AV(  1 3  CO) values  f o r other  from  Sharpless  Knapp e t a l . (1976) r e g i o n s by S e w a l l  91  (1980). S e w a l l  (1980) f o u n d t h e r a t i o  g e n e r a l l y about  five.  their  two  Sewall  (1980) f o u n d  12  CO  than  spectra  The r e s u l t s  of  CO) to T* ( et a l .  f o r S h a r p l e s s 222 c o n f i r m t h i s . the CO p r o f i l e s  mimicked  1 3  and  AV(  This agrees with the  CO).  1 2  Knapp  profiles 1 3  T* (  AV(  1 2  1 3  C O ) was  (1976) f o r Furthermore,  t h e shape o f t h e  C O ) was a p p r o x i m a t e l y results  1.5 t i m e s  of  Knapp  wider et a l .  (1976). Why  do  possible Sewall one  13  reason  CO  1 3  profiles  i s that  (1980) f o u n d  the CO l i n e  the o p t i c a l  i s a lower  could  CO  limit  be n a t u r a l  i f they  similar.  depth  CO  the  excitation same  different regions each  T^ (  1 2  the  two  profiles  i s the case  and  1 3  although this i s  CO lines  to  be  i s the d e t e r m i n a t i o n of the  Normally,  isotopic  that  1 2  1 2  the  remembered  shapes f o r C O  f o r t h e C O and  If  saturated.  d e p t h . As a r e s u l t ,  line  T  G A  (  1 3  CO)  excitation  species  i s taken t o  temperatures  then  f o r the  would be d r a s t i c a l l y forcold  dark  s u c h a s we h a v e , t h e two p r o f i l e s  were  cooler  different  globules. are similar  For  be  from  warmer  since  both  be s a t u r a t e d . infrared  (Figure  14) shows  infrared  stars  photograph there  and  CO  from  i s very  of i n f r a r e d  stars.  the  little  Steward  1 2  CO  They a r e i n f r a r e d  Observatory  coincidence  h o t s p o t s . One i n t e r e s t i n g  become a p p a r e n t . S u r r o u n d i n g o u r 13 K sets  be  transitions,  problem  CO).  f o r t h e two  could The  related  temperature.  other. This  regions lines  as  must  similar  saturated  CO p r o f i l e s ? A  1 3  1 3  t o observe  1 2  f o r t h e C O was a t l e a s t  f o r the CO o p t i c a l  a r e both  Another  the  is partially  1 3  not a n e c e s s a r y p r e r e q u i s i t e  13  mimick  i n t h e c a s e o f S h a r p l e s s 152. I t  this it  the  contour stars  between  feature d i d are  three  #2, #3, and t h e  92  six  stars  surrounding  Lk Htv 1 0 1 .  This  interesting  coincidence  appears t o agree with p r e d i c t i o n s of the ' B l i s t e r ' 1977,  Gilmore  inside  t h e s u r f a c e s of l o n g m o l e c u l a r  initiated cloud. star  1978).  on  this  The CO h o t s p o t s would t h e n  derived  (Tenorio-Tagel Sharpless  stars.  Lk  would  classify  generation  222  Lk H « 1 0 1  sequence.  star  as  The  the other  spots  are  and  Roger's  (1981) HCX101  infrared  stars  appear  to  have  HI  global  the  CO  anticorrelation of  and  i n the  three  difference  stage  infrared  stars  most  (  in  1  979)  their  a r e the next  stage  recent  peak HI c o n t o u r s are no  coincident. relation  features  the  CO h o t s p o t s . T h i s  o f t h e same stage  that  than  r e g i o n s . The HI  the  1 2  CO  which  visual  extinction  correlation  between  in  with  the higher  and t h e s i x The  other  t o t h e HI there  data.  is  an  l i e t o the  i n d i c a t e s t h e two s t u d i e s velocity  could  between t h e CO and HI p a r t i c l e  agreement  Champagne  g e n e r a t i o n s of  between t h e two. The peak HI c o n t o u r s  a r e mapping d i f f e r e n t larger  of  formation.  Lk  northwest  generation  fourth  the  around  Comparing  is  i n t o the  s t a r . H a b i n g and I s r a e l  stars  The  next  there are probably  infrared  much  the  w h i c h c o u l d be c l a s s e d a s t h e f i r s t  Dewdney  formation  1979).  s e q u e n c e . The CO h o t precedes  be  m o d e l s f o r HII r e g i o n s  i s the i n i t i a t i n g  HCV101  evolutionary  clouds. Star  just  S i m i l a r b u t f a r more q u a n t i t a t i v e r e s u l t s were  using numerical  In  (Israel  model OB a s s o c i a t i o n s form  one s i d e o f t h e g i a n t c l o u d and p r o c e e d s  formation.  model  In  model  contours  half  width  is  be e x p l a i n e d by t h e  masses. show  a  reasonable  and CO warm r e g i o n s . T h i s i s  t h e work o f Dickman  (1978) and F r e r k i n g e t a l .  93  (1981).  The peak HI  extinction  is  emission  lower  occurs  than  average.  presumably  been a b l e t o d i s s o c i a t e  where  is  A  v  asymmetry density  lower.  quite  near  HI  i s 13 x  10  estimates Sewall  well  and  by  must  for Sharpless  and  Roger  (1981) may  the  They  corresponding  find H  visual  extinction  within  other  Our  (1981), 1 3  CO  Using  by  Dewdney  extinction is  between  cloud i s o p t i c a l l y  thin.  optical  depth  quite  ( CO)  results  is  13  C 0 L  already  suggest  2.8  of  x 10  x 10  1 S  Knapp cm  atoms  2 2  f o r the et a l . with  - 2  cm  1.4  1 3  CO  column d e n s i t i e s  (1981) have f o u n d analysis  and  x 10  atoms  2 1  Roger our  1 3  a  and  - 2  a  i s well  cited.  peak  same  high  by Dewdney  v  i m p l i e d from 8 and  was  one.  the  CO  15 m a g n i t u d e s  are well within other estimates 1980).  Both  as used  t h e peak HI column d e n s i t y i m p l i e d w o u l d be  of  mass of HI o f 8 5 M .  o f e l e v e n m a g n i t u d e s . T h i s v a l u e of A  the  data  found  the  using  same as Dewdney and Roger (1976).  discontinuity  (1981) a l s o make a r o u g h e s t i m a t e  N  estimates  results  this  0  column d e n s i t y of 2.1  a  northwest  r e g i o n s and so t h e a s s u m p t i o n  column d e n s i t y  (1976).  the  has  t h e peak column d e n s i t y f o r  emission  not be a good  Dewdney and Roger CO  steep  and a t o t a l  - 2  that  >, 1 )  13  to  star  (1981) have m o d e l e d  a  (1981) f i n d  assume  ( X  peak  i n t o HI  a  assuming  Roger  (1980) f o u n d  exciting  visual  to the e a s t .  atoms c m  2 0  H  The  Dewdney and Roger  Lk Hoc 1 01  Dewdney  i n r e g i o n s where t h e  cm .  from  Knapp  from  our  The v a l u e  results  f o r each of the  (Table V I I I ) .  generated  is precisely  (1981).  (Thompson  et a l .  by Dewdney and Roger  This  - 2  e x a c t l y the  of t h e  These v a l u e s  et a l .  1977,  that  visual clouds of  k  v  Cohen  94  Finally,  one  can  c a l c u l a t e t h e mass o f e a c h o f t h e c l o u d  fragments  from  their  The  size  i s defined  cloud  generated mass u s i n g cloud  C0  1 3  the v i r i a l  the  1 3  CO  rough  estimate  be u s e d  where (1.67 atomic  A  is  R  radius  limit.  to estimate  and  AV  mass  the c l o u d  area,  is  of  C0  our  assuming  A the  o r by  give,  i s the l i n e  1 3  of  by t u r b u l e n c e ,  stability  The g e n e r a t e d  density.  C 0 ) , contours. by  V ° ^ r . Both  the v i r i a l for  the p r o j e c t e d  units),  1 3  power  (EVKttS  x 10 ~ * g r a m s ) , y U , i s t h e mass  (  A  A V  Note t h a t  2  T  column  half  supported  c o l l a p s e with  required  an u p p e r  to  temperature,  C0  1 3  t h e o r e m c a n be computed  the cloud  profiles.  probably also  fall  £  M  is  as the width  i s in equilibrium,  assuming a f r e e  R  and t h e g e n e r a t e d  radiation  fragment  where  size  the  column  J^8l)  h a l f width of only  a  very  cloud.  It i s  density  can  hydrogen  mass  mass. Then,  m  H  i s the atomic  mean  X i s the r a t i o  molecular of H  a  to  1 3  C0  weight from  (2.33  Dickman  95  (1978),  and  N  significantly replaced area,  is over  A,  is  summary  poorly  column  extent  density.  of  the  If  cloud,  the cloud  of  the  The  a compromise  clouds  (1981) since  their  obtained  masses  by  the  t h e two e s t i m a t e s . gives  the  d i s the  c a l c u l a t e d by b o t h methods  fragment  The  the  differ  i s probably  work  masses  r e s u l t s have c o n s i d e r e d  large.  IX and X g i v e a  two  best  be  projected  2  and  probably  their  The  a n d depends on d , where  The t r u e mass o f e a c h c l o u d  between  varies  t h e u n c e r t a i n t i e s i n t h e mass a r e  masses  significantly.  N  A•N s h o u l d  area.  t h e masses a r e u n d e r e s t i m a t e d . T a b l e s  methods.  clouds  C0  defined  As a r e s u l t ,  Generally,  al.  the  1 3  by a sum o f t h e A « N o v e r  distance.  et  the  of  Frerking  f o r t h e s e warm problem  of  CO  isotope f r a c t i o n a t i o n . The  13  calculate Dickman total  C0  column  the t o t a l  given  star  counts give  i n Table  densities.  Due  should  densities visual 1 3  CO  C O L  to  to the large  1 3  C0  upper  extinction, A  v  CO),  enables  density,  . This  N,  i s easily  one using  converted  e x t i n c t i o n s found  than  those  those  using limits.  , is fairly  the  from  the  results.  generated  We f e e l  close  the to  from t h e  u n c e r t a i n t i e s i n the star on  to  e x t i n c t i o n . The r e s u l t s  column counting  The  visual  from t h e s t a r c o u n t s a r e p r o b a b l y found  are l i k e l y  1 3  and v i s u a l  too heavily  those  (  column  r e s u l t s much l o w e r  determined  whereas  N  V I I I . The v i s u a l  not r e l y  extinctions low  of  hydrogen d e n s i t y  are  one  molecular  (1978) r a t i o  atomic  density,  1 3  f a r too  CO  column  the true value  t o those  given  of the  by  the  analysis. One  relative  final  c a l c u l a t i o n , was  made t o d e t e r m i n e  v e l o c i t y d i f f e r e n c e between  clouds  if  t h e maximum  they  were  in  96  Keplerian Lk  HCV101  they are  orbits  give  density  km  This  is km  1  s ~ . Since 1  the  to  HCV101  largest and  mass,  note  neighbours.  velocity difference  spectrometer that  the  possible.  no  further  #2  located  were c h o s e n  relative velocity  nearest  the  #1 and  (0.0,-10.8)  velocity  expected  From  the  i s at  most  conclusions  on  They 13  resolution.  are  at  since  difference.  CO  0.35 It  was  0.4  below  our  observed d i f f e r e n c e  velocity differences  resolution  c l o u d s are  Lk  i s below the  interesting  velocity  the  most m a s s i v e  column s~ .  and  (7.2,-10.8)  would the  about e a c h o t h e r . C l o u d s  t h i s aspect  of  the  £>7  Table  VIII For  given.  -Peak  extinction  N  C O L  C O L  are  1 3  C O ) and R e l a t e d  H  a  clouds  column  calculated.  A  v  t h e peak  density  1 3  and  The l a s t  a  found u s i n g  NccJHj  an  estimate  =  Dickman's  column  of the v i s u a l  x  10  gives  the  ( 1978)  (5.0 + 2.5)  C 0 column d e n s i t y i s corresponding  e x t i n c t i o n from t h e s t a r c o u n t s o f  ( 2 H ) was  Then  (  each of the f i v e  The t o t a l  visual  N  visual  t h e measured  Palomar  prints.  ratio,  N  5  C O L  (  1 3  CO)  extinction, A , v  was  determined  using,  <N(H,  (Bohlin  to  Dickman as  those  account  3k  e t a l . 1978) and A  Frerking H  + H )/E(B-V)>  atoms c m  2 1  3  result  1  6  namely and g i v e s  a larger value  1.0 x 1 0 . 6  column  i n d i c a t e d a b o v e . The F r e r k i n g t h e c a r b o n monoxide  mag"  - 2  = 0.76A .  e t a l . (1981) have d e r i v e d  ' CO abundance, (1978)  v  = 5.8 x 1 0  isotope  This  is  twice  d e n s i t i e s twice ratio  (1981)  fractionation.  f o r the the  as l a r g e  takes  into  98  Cloud  Generated N„u(  1 3  (xlO . 1  4  N(2H ) (xlO cm )  A star counts  a  C0)  2 2  cm )  v  -2  2  #l-(7.2,-10.8)  287  2.9  15.5  4.0  #2-(0.0,-10.8)  271  2.7  14.6  1.5  #3-(7.2,-5.4)  205  2.1  11.0  2.4  #4-(3.6,-5.4)  193  1.9  10.4  2.2  #5-(0.0,-1.8)  147  1.5  7.9  2.9  99  Cloud  C0 3.5 1 3  Size k 3.0 k  Mass Mo  Density (xlO ) amu/cm 5  3  #l-(7.2,-10.8) #2-(0.0,-10.8) 3000  #3-(7.2,-5.4) #4-(3.6,-5.4) #5-(0.0,-1.8)  N o t e : 1 = 1.67  Table  IX - V i r i a l Table  two  x 10  Cloud  corresponding  1 3  CO  virial  3 4  cm  area  2  1.2  530 / \ 1760 160 \  1.9 1.1  180  2.9  J  128  f o r the  1 3  370  CO  6.7  size.  Masses  IX i n d i c a t e s  different  average  230  420~A  the s i z e  radiation mass  d e n s i t y i s given  of each c l o u d c o n t a i n e d temperature  assuming  i n the l a s t  contours  spherical  within  and  symmetry.  column o f t h e t a b l e .  the The  100  N ( C0) Size cm - M (xlO 12.5 10 >15  Mass  #l-(7.2,-10.8)  241^  49V  #2-(0.0,-10.8)  186  #3-(7.2,-5.4)  128 \  #4-(3.6,-5.4)  59/  #5-(0.0,-1.8)  7  Cloud  1 3  Density (xlO ) amu/cm 4  1 5  N o t e : 1 = 1.67 x 10-  Table  X -N This  three  C O L  (  1 3  given  1 3  1 3  CO  i n the l a s t  1.0 x 1 0 . 6  CO  2  column d e n s i t y Frerking  fractionation.  19 area  7  ?  218 for the  3  C0)  column  of each c l o u d density  column d e n s i t y  1.2  25  0.7  size.  is  twice  masses  twice  takes  contained  contours  and  within the  mass. The a v e r a g e d e n s i t y i s  column o f t h e t a b l e .  ratio  1.2 440 1.8  the s i z e  a l a r g e r value This  41J{ 370  2490  1730  1.0  Masses  gives  different  have d e r i v e d  The  CO) Cloud  table  corresponding  cm  4  1  3  f o r the H  a  Frerking to  t h e Dickman  1 3  CO  abundance,  (1978) r e s u l t  as l a r g e as those  i n t o account  et a l .  (1981) namely  and g i v e s  indicated  above.  t h e p r o b l e m o f CO  isotope  F i g u r e 19 - Comparison o f  1 2  C 0 , HI, A  v  etc.  F i g u r e 19 i s an enlargement o f the red Palomar The s c a l e s i z e i s 6.27 m i l l i m e t r e s per 1.8 a r c m i n u t e  briht  interval  f i g u r e 7 - I n t e g r a t e d "CO The  T* ("CO)  is  integrated  F i g u r e 7. The d e c l i n a t i o n shows f i v e CO hot s p o t s (7.2,-5.4),  Contours over a l l v e l o c i t i e s t o g i v e  (DEC) v e r s e s r i g h t a s c e n s i o n (RA) p l o t located  at  (7.2,-10.6),  ( 3 . 6 , - 5 . 4 ) , and ( 0 . 0 , - 1 . 6 ) . The c e n t r e (0.0,0.0) i s ,  cx(1950) • 04 26"34'.0 H  £ ( 1 9 5 0 ) * 35*13'00*0  (Right Ascension) (Declination)  (0.0,-10.6),  f i g u r e 9 -Generated The  TJ  ("CO)  observations. The declination  ("CO)  (DEC)  Contours  contours  are  generated  frorr  "CO  steps.  The  contour  units  are o n e  kelvin  verses  right  ascension  (RA) plot shows the  sane f i v e CO hot spots present i n Figure 7 ( T { ("CO) The centre (0.0,0.0) i s , O((1950) - 04"26 34!0 n  6 (1950) - 35*13'00*0  (Right  Ascension)  (Declination)  Contours).  F i g u r e 10 G e n e r a t e d The  N (**CO) ML  observations. declination  The  N  C O t  ( " C O ) Contours contours  contour  are units  generated are  (DEC) v e r s u s r i g h t a s c e n s i o n  froir  1 i 10* •  (RA)  plot  dr."*.  "CO The  shows t h e  same f i v e CO h o t s p o t s p r e s e n t i n F i g u r e 7 (T " (**CO) C o n t o u r s ) . A  To d e t e r m i n e N , {''CO), t0  the r a t i o (see  Z V C ' C O ) t o AV(»»CO) was  found  to  be  1.52 ± 0.04  T a b l e I l l - P r o f i l e H a l f Width R a t i o s ) . The c e n t r e (0.0,0.0)  is,  o((1950) - 0 4 26' 3«!0 -  ,  6(1950) « 35 13'00*0 e  (Right Ascension) (Declination)  Figure  ( V r 5500 A ) ,  13 .  The magnitudes of standard  procedure  extinction  outlined  Theory, Data, and R e s u l t s . represent  the i n t e r v a l  A  E x t i n c t i o n Contours  were  determined  i n section  The of  v  numbers  using  III.6-Star on  each  the  Counting  contour  map  e x t i n c t i o n . For example, a 4 would  i n d i c a t e the e x t i n c t i o n i s between 3 and 4 magnitudes.  T h e  conversion procedure i s o u t l i n e d i n Dickman 197E.Centxe (0.0,0.0),  cx<1950) - 04* 26"34*.0 6 (1950) - 35 13'00.'0 B  (Right Ascension) (Declination)  102  F i g u r e 14 - I n f r a r e d D i a g r a m Figure print  14  is  a  s c h e m a t i c r e p r e s e n t a t i o n of t h e  (B000 t o 9000 A) s e n t  Observatory, converging  by  Oniverstiy  of  D r . E. C r a i n e Arizona,  W  ,  6 ( 1 9 5 0 ) - 35 13'O0"0 e  Lk H°Q01 i s i n d i c a t e d by our  Tuscon,  a r r o w s i s t h e c e n t r e of our s u r v e y  a ( 1 9 5 0 ) - 04 26' 34'.0  observation  field  10 are  and  of  the  infrared Steward  Arizona.  The  field,  (Right Ascension) (Declination)  the other  numbered.  The  infrared  stars  in  d e t a i l s of e a c h a r e  summarized i n T a b l e V l l - I n f r a r e d S t a r P o s i t i o n s .  €>  tt>Z  Figure  17  show HI e m i s s i o n  The integrated  km s ' .  The c o n t o u r  cm  column  -  - 2  in  over  the velocity  steps correspond  density.  to  -6  range  i n t e r v a l s of  (Dewdney a n d R o g e r  contours to  +10  x  10 °  1.5  1981).  2  f  103  V. In the  conclusion,  HII  region  i s less  extended  region  Visually,  NGC  arcminute  shell  Our K),  but  and  west  emission which in  with  five  hot  the  12  five  CO  hot  13  Their  of  was  not  CO  the  of  Lk  t o 20  and  (0.0,-10.8),  clouds  derived 25M  #4  Lk  and  we  find  peak  contours  the an  found  a  We  north  suspect  of  one  the  magnitude,  T*  1 2  CO),  l a r g e fragmented  13  CO  data  12  CO  and  Lk  #1,  Hcvi 01  were 13  envelope  CO  is  10  region  of Lk  CO  CO  K  are  clouds  (0.0,-1.8).  They  25M . A l l o f  @  13  #2,  resolved.  densities  1 1 M and  same  located  unresolved  HaiOl  have masses o f  have  (7.2,-10.8),  column  Lk  the  emission  (7.2,"5.4) are 13  from  contours  H<X101  and  in  generated  T^  (3.6,-5.4)  S  12  CO  contour  (3.6,-7.2). CO  data  to  anticorrelation of  (10  (  other  and  emission  temperature,  Two  #5  CO  u n d e t e r m i n e d . The  respectively.  embedded  HcnOl  Comparing data,  Q  24  s e v e r a l degrees  clouds  #3,  12  extinction  from c a l c u l a t e d  HCX101  fragments are on  CO  a  K.  the  single  by  d e g r e e wide and  we  observed  HCX101.  l o c a t e d a t Lk  centered  up  within a  0  are  field  more  arcseconds.  surrounded  determined.  a visual  radiation  32  a  of  light.  as y e t  been  n e a r l y one  spots  49M , 4 1 M , and are  f a r as  survey  masses  G  have  r a d i o core with  to  nebula  of  are  The  across  out  arcminute  o b s e r v a t i o n s . Both  southeast HCX101  five  average  spots  arcsecond  show a wide r e g i o n of  area  our  Since  Lk  an  star.  emission  boundaries  e x t e n d s as  Within  one  of weaker e m i s s i o n  boundaries  l e n g t h . The  K.  is a  exact  covers  i s a BO.5  weaker  results  the  HonOl  than  of  1579  CO  12  Lk  CONCLUSIONS  the  two  Dewdney and between  s t u d i e s . The  the HI  Roger's  (1981)  HI  positions  of  the  contours  l i e to  the  1 04  northwest  o f t h e CO c o n t o u r s .  This  indicates  different  t r a c e r s a r e mapping  separate  half  i s larger  f o r the  width  column d e n s i t i e s The  in  from b o t h  visual  correlation  between  is  presumably  been a b l e  where  is  A  v  asymmetry density  well  CO.  than  stars.  occurs  average. H  The  we  our  assuming  13  K  1 2  CO  They a r e i n f r a r e d  1978).  observe  resolution 1 3  CO  cm" . 2  reasonable  to  visual  star  the  has  northwest  (1981) have m o d e l e d  a  steep  contour stars  this  discontinuity  (Table V I I ) . This  are  #2,  of  Star  formation  was  would be t h e n e x t  will  require  of the r e g i o n  likely  observations  throughout  #3,  and  generation  on  the r e g i o n .  model  s e t s of the  (Israel  initiated  inwards.  a more d e t a i l e d  centered  three  six  interesting configuration  of t h e c l o u d and has p r o c e e d e d  Confirmation  a  exciting  i n t o HI  a  the p r e d i c t i o n s of the ' B l i s t e r '  spots  atoms  2 1  i n r e g i o n s where t h e  agrees  outskirts  TO  (1978) and F r e r k i n g e t a l .  Lk Hod 01  Gilmore  x  HI  and CO warm r e g i o n s . T h i s i s  v  surrounding with  velocity  The d e r i v e d peak  show  Dewdney and Roger by  two  Lk HO<101 t o t h e e a s t .  Surrounding infrared  A  to d i s s o c i a t e  lower.  quite  near  emission  lower  12  contours  the higher  these  r e g i o n s . The HI  t r a c e r s are ^1.3  t h e work of Dickman  The peak HI  extinction  that  extinction  agreement w i t h  (1981).  than  that  The  of i n f r a r e d mapping  with  1977, on t h e  CO  hot  stars. better  Lk H#1 0 1 (3.6,-7.2)  and  105  BIBLIOGRAPHY Allen,  D.A.  1973,  Monthly N o t i c e s Royal  Allen, CW. 1963, Astrophysical L o n d o n , London, A t h a l o n e P r e s s .  Astron.  Quantities,  A l t e n h o f f , W.J., B r a e s , L . L . E . , O l n o n , F.M., 1976, A s t r o n . A s t r o p h y s . 46:11. B e r n e s , C. Bohlin,  1979,  R.C.,  Astron. Astrophys.  Savage, B.D.,  and  1937, "The D i s t r i b u t i o n of C h i c a g o P r e s s .  Blitz,  and  L.,  Lada, C.J.  B r a u n , R. 1980, P h y s i c s of B r i t i s h C o l u m b i a . Brown, R.L., N o t i c e s Royal  1979,  449  Broderick, A s t r o n . Soc.  1980,  Cohen, M.,  and  Dewhirst,  Cohen, M.,  and  Kuhi,  Cohen, M.,  and  Woolf, N.J.  Craine,  1981,  E.  of  Stars  J . 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Turner, Ulich,  B.E.  1971, A s t r o p h y s .  B.L., and Haas, R.W.  W i l s o n , E.W., 143:1*161. Wilson, W.J., 183:871. Zuckerman, Astrophys.  Jefferts,  B., and 12:279.  8:73.  1976, A p . J . S u p p l .  K.B.,  Schwartz,  Lett.  and  P.R.,  Palmer,  P.  Penzias, and 1974,  30:247. A.A.  1970,  Ap.J.  E p s t e i n , E . E . 1973, A p . J . Annual  Review  Astron.  108  APPENDIX: T / " ( In  this  The  III.3. the  In t h e s e  represent  T  ( CO) contours 1 2  A  f o r t h e J=1—»0 t r a n s i t i o n  method  contour  C O ) CONTOURS AT CONSTANT VELOCITY  a p p e n d i x we p r e s e n t  L.S.R. v e l o c i t y 222.  1 2  of  reduction  f i g u r e s we s p e c i f y  interval  ( K ) . The  is  of  1 2  CO  described  at constant  in fully  Sharpless in section  t h e i s o t o p e , the v e l o c i t y and contour  t h e a v e r a g e peak t o peak n o i s e  unit  was  f o r the data.  chosen  to  109  n  12.0  9.333 _J  6.667 I  RA. 4.0 _l  ARCMIN. 1.333 I  -1.333 1  -4.0  -6.667  -9.333  -]2o0  -9.333  -12.0  L H 1 0 ) 12C0 CONTOUR UNIT VELOCITY  12.0  -.2.00 K  -3.85  9.333  KM/SEC.  6.667  4.0  i  RR  1.333  ~  r  -] 333  ARCMIN .  -4.0  I -6.667  110  9.333  o !2.0  _J  LH101  VELOCITY  4.0  _ j  I  12C0^^  CONTOUR  7  6 66T  1.333 I  -1.333 I  ?  UNrr\-.2.00 -3.20  Rfl. ARCMIN.  Kj  KM/SEC.  \  cr  1  12.0  9.333  6.661  4.0  1.333  1  -1.333-  Rfl. ARCMIN.  -4.0 1  -6.667  -9.333  -J2cO  DEC. -14.D  I  •14.0  — JI .111  I  -11.111  -B.222  I  -R.222  ARCMIN  -5.133  -2.444  I  -5.333  I  -2.444  DEC.  0.444  '  0.444  ARCMJN  3.3.33  I  3.333  6.222  '  6.222  .9.111  '  9.1)1  !2.0  !  is,  12.€  1 12  RA. a 12.0  9.333  6.66')  4.0  ARCMIN. 1.333  RA.  . -1.333  ARCMIN.  -4.0  -6.667  -9.333  -12<rf)  113  RA.  ARCMIN.  114  Rfl. 10.111  o 13.0  LH101  7.222  4.333  ARCMIN. 1.444 -1.444 I 1  —  -4.333 1  -7.222  -10.11)  -13o0  12C0  CONTOUR  mnj-2  VELOCITY.^TeO  KM/SEC  DC cr  cr  o LU o  LU a  13.0  10.111  7.222  -1  4 333  r — 1 1.444 -1.444 Rfl. ARCMIN.  1  -4.333  -i -7.222  1  -10.111  -13.0  1 1 5  116  a 13.0  LH101  10.111  4.333 __1  7 .222 I  Rfl.  ARCMIN. -1 .444 1.444 _l 1_  -4.333 _J  -7.222 I  -10.111 I  -13trfl  12C0  CONTOUR  UNtT  VELOCITY  0.70  :2.00  K  KM/SEC  s: Qi cr  UJ a  13.0  10.111  T" 7.222  —1 4.333  1 1 1.444 -1.444 Rfl. APvCMIN.  "T"  -4.333  -7.222  -10.111  -13.0  !i n  I  

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