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J/A+A/330/676       IRC+10216 Silicon and sulfur chemistry (Willacy+ 1998)
Silicon and sulfur chemistry in the inner wind of IRC+10216
       Willacy K., Cherchneff I.
      <Astron. Astrophys. 330, 676 (1998)>
      =1998A&A...330..676W      (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Stars, giant

Keywords: molecular processes - stars: AGB - stars: individual: IRC+10216


Abstract:
    We present a dynamical and chemical model of the inner wind of the
    carbon-rich, AGB star IRC+10216. We include the effect of
    pulsation-driven shocks on the gas envelope close to the stellar
    photosphere and construct an extended chemical model that includes in
    particular the chemistry of hydrocarbon species and silicon and
    sulphur-bearing molecules. The derived theoretical abundances for many
    molecules are in excellent agreement with values obtained from
    observations of infrared ro-vibrational molecular lines. We confirm
    the ``parent'' character of certain chemical species and show that the
    inner wind of IRC+10216, and more generally of evolved AGB stars, is
    an active dynamical and chemical region where molecules are formed and
    processed.
Objects:
    ----------------------------------------------------------
       RA   (2000)   DE    Designation(s)
    ----------------------------------------------------------
    09 47 57.2 +13 16 44   IRC +10216 = CW Leo
    ----------------------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table5           135      352   The reaction set
table5.tex       177      453   LaTeX version of table5


Byte-by-byte Description of file: table5

   Bytes Format Units   Label     Explanations

   1-  3  I3    ---     Num       Sequential number for the reaction
   5- 74  A70   ---     Reac      Reaction
  76- 77  I2    ---     Dnu       [-1/1] {DELTA}ν (1)
  79- 86  E8.3  ---     A         Arrhenius A parameter (2)
  89- 93  F5.2  ---     n         ? Arrhenius n parameter (2)
  96-103  F8.1  K       E         ? Arrhenius E parameter (2)
 106-135  A30   ---     Ref       Reference (3)

Note (1): ν is the stochiometric factor

Note (2): Rate in the Arrhenius form k = A (T/300)nexp(-E/T)
           Where A has a value of 0.0 the rate is calculated from equation 4
           using the parameters for the previous reaction listed.
           T is the gas kinetic temperature
Note (3): The references are:
            R95:  Millar et al., 1997A&AS..121..139M
           ER95:  estimated using rates from Millar et al., 1997A&AS..121..139M
                   (The reaction used as the source of the rate is given)
            CBT:  Cherchneff et al., 1992ApJ...401..269C
       Baulch92:  Baulch et al. 1992, J. Phys. Chem. Ref. Data 21, 411
           NIST:  Mallard et al. 1994, NIST Chemical Kinetics Database: 
                   Version 6.0, National Institute of Standards and Technology, 
                   Gaithersburg (MD)
         Mackay:  MacKay, 1995MNRAS.274..694M
              E:  an estimated rate for a collider reaction. Those reactions for
                   which the reverse rates are calculated by using
                   thermodynamics are shown by ←>, the reverse for all other
                   reactions is given explicitly in the ratefile.


Acknowledgements: Isabelle Cherchneff 

(End)                                         Patricia Bauer [CDS]   22-Sep-1997