Query : 2011A&A...526L..11C

2011A&A...526L..11C - Astronomy and Astrophysics, volume 526, L11-11 (2011/2-1)

Water in IRC+10216: a genuine formation process by shock-induced chemistry in the inner wind.


Abstract (from CDS):

The presence of water in the wind of the extreme carbon star IRC+10216 has been confirmed by the Herschel telescope. The regions where the high-J H2O lines have been detected are close to the star at radii r≤15R*. We investigate the formation of water and related molecules in the periodically-shocked inner layers of IRC+10216 where dust also forms and accelerates the wind. We describe the molecular formation by a chemical kinetic network involving carbon-and oxygen-based molecules. We then apply this network to the physical conditions pertaining to the dust-formation zone which experiences the passage of pulsation-driven shocks between 1 and 5R*. We solve for a system of stiff, coupled, ordinary, and differential equations. Non-equilibrium chemistry prevails in the dust-formation zone. H2O forms quickly above the photosphere from the synthesis of hydroxyl OH induced by the thermal fragmentation of CO in the hot post-shock gas. The derived abundance with respect to H2 at 5R* is 1.4x10–7, which excellently agrees with the values derived from Herschel observations. The non-equilibrium formation process of water will be active whatever the stellar C/O ratio, and H2O should then be present in the wind acceleration zone of all stars on the Asymptotic Giant Branch.

Abstract Copyright:

Journal keyword(s): astrochemistry - molecular processes - stars: low-mass - stars: carbon - stars: AGB and post-AGB

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 V* IK Tau Mi* 03 53 28.8884898148 +11 24 21.865959095 16.99 17.03 13.39 7.29 3.20 M7-11 590 0
2 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2199 0
3 * chi Cyg S* 19 50 33.9243904 +32 54 50.609683 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 671 0
4 V* VY Cyg cC* 21 04 16.6365398971 +39 58 20.104204896 11.74 10.66 9.56   8.090 F5.5-G0.5Ib 129 0

    Equat.    Gal    SGal    Ecl

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