2015A&A...582A.102O


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.25CET09:35:18

2015A&A...582A.102O - Astronomy and Astrophysics, volume 582A, 102-102 (2015/10-1)

Detection of CI line emission from the detached CO shell of the AGB star R Sculptoris.

OLOFSSON H., BERGMAN P. and LINDQVIST M.

Abstract (from CDS):

Stars on the asymptotic giant branch (AGB) lose substantial amounts of matter, to the extent that they are important for the chemical evolution of, and dust production in, the Universe. The mass loss is believed to increase gradually with age on the AGB, but it may also occur in the form of bursts, possibly related to the thermal pulsing phenomenon. Detached, geometrically thin, CO shells around carbon stars are good signposts of brief and intense mass ejection. We aim to put further constraints on the physical properties of detached CO shells around AGB stars. The photodissociation of CO and other carbon-bearing species in the shells leads to the possibility of detecting lines from neutral carbon. We have therefore searched for the CI(3P1-3P0) line at 492GHz towards two carbon stars, S Sct and R Scl, with detached CO shells of different ages, ≃8000 and 2300 years, respectively. The CI(3P1-3P0) line was detected towards R Scl. The line intensity is dominated by emission from the detached shell. The detection is at a level consistent with the neutral carbon coming from the full photodissociation of all species except CO, and with only limited photoionisation of carbon. The best fit to the observed 12CO and 13CO line intensities, assuming a homogeneous shell, is obtained for a shell mass of ≃0.002M, a temperature of ≃100K, and a CO abundance with respect to H2 of 10–3. The estimated CI/CO abundance ratio is ≃0.3 for the best-fit model. However, a number of arguments point in the direction of a clumpy medium, and a viable interpretation of the data within such a context is provided.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - circumstellar matter - stars: mass-loss - radio lines: stars - stars: individual: R Scl - stars: individual: S Sct

Simbad objects: 14

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Number of rows : 14

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* R Scl C* 01 26 58.0946233986 -32 32 35.437732667 17.26 9.59 5.72 3.69 2.30 C-N5+ 301 0
2 RAFGL 618 pA* 04 42 53.6245215366 +36 06 53.397219192   16.32   12.59   C-rich 960 0
3 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1489 0
4 HD 44179 pA* 06 19 58.2185496 -10 38 14.706068 9.51 9.33 9.02     B9Ib/II 723 0
5 HD 56126 pA* 07 16 10.2589670319 +09 59 47.953674864   9.20 8.32     F0/5Ia 303 0
6 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2156 0
7 V* S Sct C* 18 50 20.0367524071 -07 54 27.430964220 13.93 9.89 6.80     C-N5 196 0
8 M 57 PN 18 53 35.0969571234 +33 01 44.883146221   15.405 15.769 15.901 16.062 DA(O?) 794 2
9 V* TT Cyg C* 19 40 57.0159854799 +32 37 05.755486755   10.43 10.20     C-N5- 187 0
10 V* AX Cyg C* 19 57 12.5070124708 +44 15 40.033878504 12.97 11.28 7.85     C-N5- 82 0
11 V* RT Cap C* 20 17 06.5288478069 -21 19 04.462721142   12.92 8.90     C6,4 115 0
12 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 835 1
13 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2338 1
14 NGC 7293 PN 22 29 38.5453078023 -20 50 13.746093105 11.894 13.158 13.524 13.689 13.898 DAO.5 902 0

    Equat.    Gal    SGal    Ecl

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2020.10.25-09:35:18

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