Justtanont, K., Decin, L., Schoier, F. L., Maercker, M., Olofsson, H., Bujarrabal, V., Marston, A. P., Teyssier, D., Alcolea, J., Cernicharo, J., Dominik, C., de Koter, A., Melnick, G., Menten, K., Neufeld, D., Planesas, P., Schmidt, M., Szczerba, R. ORCID: 0000-0003-2886-4460, Waters, R., de Graauw, Th., Whyborn, N., Finn, T., Helmich, F., Siebertz, O., Schmuelling, F., Ossenkopf, V. and Lai, R. (2010). A HIFI preview of warm molecular gas around chi Cygni: first detection of H2O emission toward an S-type AGB star. Astron. Astrophys., 521. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 0004-6361

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Abstract

Aims. A set of new, sensitive, and spectrally resolved, sub-millimeter line observations are used to probe the warm circumstellar gas around the S-type AGB star chi Cyg. The observed lines involve high rotational quantum numbers, which, combined with previously obtained lower-frequency data, make it posible to study in detail the chemical and physical properties of, essentially, the entire circumstellar envelope of chi Cyg. Methods. The data were obtained using the HIFI instrument aboard Herschel, whose high spectral resolution provides valuable information about the line profiles. Detailed, non-LTE, radiative transfer modelling, including dust radiative transfer coupled with a dynamical model, has been performed to derive the temperature, density, and velocity structure of the circumstellar envelope. Results. We report the first detection of circumstellar H2O rotational emission lines in an S-star. Using the high-J CO lines to derive the parameters for the circumstellar envelope, we modelled both the ortho-and para-H2O lines. Our modelling results are consistent with the velocity structure expected for a dust-driven wind. The derived total H2O abundance (relative to H-2) is (1.1 +/- 0.2) x 10(-5), much lower than that in O-rich stars. The derived ortho-to-para ratio of 2.1 +/- 0.6 is close to the high-temperature equilibrium limit, consistent with H2O being formed in the photosphere.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Justtanont, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Decin, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schoier, F. L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Maercker, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Olofsson, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bujarrabal, V.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Marston, A. P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Teyssier, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Alcolea, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Cernicharo, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Dominik, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
de Koter, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Melnick, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Menten, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Neufeld, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Planesas, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schmidt, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Szczerba, R.UNSPECIFIEDorcid.org/0000-0003-2886-4460UNSPECIFIED
Waters, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
de Graauw, Th.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Whyborn, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Finn, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Helmich, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Siebertz, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schmuelling, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ossenkopf, V.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lai, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-494897
DOI: 10.1051/0004-6361/201015092
Journal or Publication Title: Astron. Astrophys.
Volume: 521
Date: 2010
Publisher: EDP SCIENCES S A
Place of Publication: LES ULIS CEDEX A
ISSN: 0004-6361
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
GIANT BRANCH STARS; MASS-LOSS RATES; CIRCUMSTELLAR WATER-VAPOR; ROTATIONAL LINE-PROFILES; EVOLVED STARS; CARBON STARS; LOSS HISTORY; W-HYDRAE; ISO-SWS; COMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/49489

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