J/A+A/545/A12 Chemistry of IRC+10216 inner wind modelled (Cherchneff, 2012)
The inner wind of IRC+10216 revisited: new exotic chemistry and diagnostic for
dust condensation in carbon stars.
Cherchneff I.
<Astron. Astrophys. 545, A12 (2012)>
=2012A&A...545A..12C 2012A&A...545A..12C
ADC_Keywords: Stars, carbon ; Models, evolutionary
Keywords: astrochemistry - stars: carbon - stars: AGB and post-AGB -
molecular processes
Abstract:
We model the chemistry of the inner wind of the carbon star IRC+10216
and consider the effects of periodic shocks induced by the stellar
pulsation on the gas to follow the non-equilibrium chemistry in the
shocked gas layers. We consider a very complete set of chemical
families, including hydrocarbons and aromatics, hydrides, halogens,
and phosphorous-bearing species. Our derived abundances are compared
to those for the latest observational data from large surveys and the
Herschel telescope.
A semi-analytical formalism based on parameterised fluid equations is
used to describe the gas density, velocity, and temperature from 1R
to 5R. The chemistry is described using a chemical kinetic network
of reactions and a set of stiff, ordinary, coupled differential
equations is solved.
Description:
The following table gives the rates by the Arrhenius expression
k=A*(T/300)n*exp(-Ea/T)
with A in s-1, cm3/s or cm6/s depending on the type of process,
bimolecular, trimolecular, and unimolecular processes, respectively.
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
tablea1.dat 123 378 The chemical reaction network ordered by
type of reactions
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See also:
J/A+A/330/676 : IRC+10216 Silicon and sulfur chemistry (Willacy+ 1998)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Code [ABCD] Code for type of reaction (1)
3- 7 A5 --- Num Reaction number (1)
9- 25 A17 --- React Reactants
27- 28 A2 --- --- [->]
32- 47 A16 --- Prod Products
52- 59 E8.3 --- A A coefficient (in s-1, cm3/s or cm6/s
depending on the type of process)
63- 68 F6.2 --- n n factor
72- 78 F7.1 K Ea Activation energy Ea in Kelvin
81-123 A43 --- Ref References for the rate data (2)
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Note (1): The chemical reaction network is sub-divided in three
categories of processes as follows:
A = termolecular (reaction labelled 3B for 3-body)
B = collisional/thermal fragmentation (reaction labelled TF
for thermal fragmentation)
C = neutral-neutral (reaction labelled NN)
D = radiative association (reaction labelled RA)
Note (2): References as follows:
E = estimated rate
NIST = National Institute of Standards and Technology Chemical Kinetics
Database
UDFA06 = UMIST database for Astrochemistry 2006
1 = Andreazza & Singh (1997MNRAS.287..287A 1997MNRAS.287..287A)
2 = Andreazza & Marinho (2005ApJ...624.1121A 2005ApJ...624.1121A)
3 = Andreazza et al. (2006MNRAS.372.1653A 2006MNRAS.372.1653A)
4 = Andreazza & Marinho (2007MNRAS.380..365A 2007MNRAS.380..365A)
5 = Andreazza et al. (2009MNRAS.400.1892A 2009MNRAS.400.1892A)
6 = Appleton, Steinberg & Liquornik (1970, J. Chem. Phys., 52, 2205)
7 = Babb & Dalgarno (1995, Phys. Review A 51, 3021)
8 = Cherchneff & Dwek (2010ApJ...713....1C 2010ApJ...713....1C)
9 = Giesen, Herzler & Roth (2003, J. Phys. Chem. A, 107, 5202)
10 = Hanson (1973, J. Chem. Phys., 60, 4970)
11 = Kruse & Roth (1997, J. Phys. Chem. A, 101, 2138)
12 = Miller & Melius (1992, Combustion & Flame 91, 21)
13 = Richter & Howard (2000, Prog. En. Comb. Science 26, 565)
14 = Self & Plane (2003, Phys. Chem. Chem. Phys., 5, 1407)
15 = Singh & Andreazza (2000ApJ...537..261S 2000ApJ...537..261S)
16 = Wakelam et al. (2009A&A...495..513W 2009A&A...495..513W)
17 = Andreazza et al. (1995ApJ...451..889A 1995ApJ...451..889A)
18 = Scherer (2000, Proceedings of the Combustion Institute 25, 1511)
19 = Woon & Herbst (1996ApJ...465..795W 1996ApJ...465..795W)
20 = Baulch (1992, J. Phys. Chem. Ref. Data 21, 411)
21 = Kumaran (1994, J. Chem. Phys. 101, 9487)
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Acknowledgements:
Isabelle Cherchneff, isabelle.cherchneff(@)unibas.ch
(End) Patricia Vannier [CDS] 09-Aug-2012