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 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:
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RA (2000) DE Designation(s)
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09 47 57.2 +13 16 44 IRC +10216 = CW Leo
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5 131 352 The reaction set
table5.tex 177 453 LaTeX version of table5
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Byte-by-byte Description of file: table5
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Bytes Format Units Label Explanations
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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)
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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 1997A&AS..121..139M
ER95: estimated using rates from Millar et al., 1997A&AS..121..139M 1997A&AS..121..139M
(The reaction used as the source of the rate is given)
CBT: Cherchneff et al., 1992ApJ...401..269C 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 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.
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Acknowledgements: Isabelle Cherchneff
(End) Patricia Bauer [CDS] 22-Sep-1997