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J/A+A/288/601     Dense molecular cores                        (Zinchenko+ 1994)
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Studies of dense molecular cores in regions of massive star formation.
CS J=2-1 and HCN J=1-0 observations of 11 northern cores
     Zinchenko I., Forsstroem V., Lapinov A., Mattila K.
    <Astron. Astrophys. 288, 601 (1994)>
    =1994A&A...288..601Z
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ADC_Keywords: Interstellar medium; Spectroscopy
Keywords: stars: formation - ISM: clouds - ISM: molecules -
          radio lines: interstellar

Abstract:
    Eleven dense molecular clouds associated with Sharpless H II regions have 
    been observed in the J=2-1 CS and C^34^S lines with the 13.7-m radio 
    telescope in Metsaehovi. In addition, we have observed a few clouds in the
    J=1-0 HCN line. Almost all of the clouds represent sites of massive star 
    formation and have been studied earlier in some other molecular lines. We 
    have compared the spatial structure of the sources as seen in the different
    lines and discuss the possible reasons for the similarities and differences
    between them. The CS emitting regions have been modelled using LVG and 
    Monte Carlo radiative transfer codes. We have found that the CS column 
    densities derived in the framework of the uniform cloud models are too low,
    in some cases probably by an order of magnitude. The most plausible 
    physical explanations involve small scale clumpiness in the clouds and/or 
    the presence of low-density molecular envelopes which shield partly the 
    emission from the core in the CS main isotope line. However the HCN data 
    do not support the hypothesis of a scattering envelope. The masses derived
    from the CS data are close to the virial masses for most sources. The 
    corresponding average densities along the line of sight are rather low, 
    n~10^3^-10^4^ cm^-3^. The densities found from the comparison with the CS 
    J=7-6 data are 2-3 orders of magnitude higher. This implies strong density
    inhomogeneities in the cores. There are size-linewidth and size-density 
    correlations similar to those found earlier for CO clouds and dense cores 
    in dark and Sharpless clouds. 

File Summary:
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 FileName    Lrecl    Records    Explanations
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ReadMe          80          .    This file
table3          35         22    CS mapping data for S76
table4          35         33    CS mapping data for S153
table5          35         25    CS mapping data for S159
table6          35         19    CS mapping data for S184
table7          35         23    CS mapping data for S199
table8          34         16    CS mapping data for S255
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See also:
    J/A+AS/111/95  : Dense molecular cores. II. (Zinchenko+, 1995)
    J/A+AS/118/191 : Dense molecular cores. IV. (Juvela, 1996)
    J/A+AS/124/385 : Dense molecular cores. V. (Zinchenko+ 1997)
    J/A+AS/133/337 : Dense molecular cores. VII. (Zinchenko+ 1998)

Byte-by-byte Description of file: table3, table4, table5, table6, table7, table8
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   Bytes Format  Units     Label    Explanations
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   2-  3  I2     arcmin    Dalpha   Gaussian line parameter Delta(alpha)
   6-  7  I2     arcmin    Ddelta   Gaussian line parameter, Delta(delta)
       9  A1     ---     l_TR*      limit flag on TR*
  10- 13  F4.2   K         TR*      Temperature scale (1)
  15- 16  I2     K       e_TR*      []? rms uncertainty on TR*
  19- 22  F4.2   km/s      DeltaV   []? Line broadening
  24- 26  I3     km/s    e_DeltaV   []? rms uncertainty on DeltaV
  28- 32  F5.1   km/s      Vlsr     []? LSR velocity
      34  I1     km/s    e_Vlsr     []? rms uncertainty on Vlsr
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Note (1):  TR* = TR/Eta_c where TR is the brightness temperature and
                Eta_c is the source coupling efficiency
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References:
   Zinchenko I.,   Paper III    1995A&A...303..554Z
   Lapinov et al., Paper VI     1998A&A...336.1007L
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(End)                                           Patricia Bauer [CDS] 23-Mar-1994