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Article: Circumstellar water vapour in M-type AGB stars: Constraints from H 2O(110-101) lines obtained with Odin

TitleCircumstellar water vapour in M-type AGB stars: Constraints from H 2O(110-101) lines obtained with Odin
Authors
KeywordsStars: Abundances
Stars: Agb And Post-Agb
Stars: Evolution
Stars: Mass-Loss
Issue Date2009
PublisherE D P Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy And Astrophysics, 2009, v. 494 n. 1, p. 243-252 How to Cite?
AbstractContext. A detailed radiative transfer code has been previously used to model circumstellar ortho-H2O line emission towards six M-type asymptotic giant branch stars using Infrared Space Observatory Long Wavelength Spectrometer data. Collisional and radiative excitation, including the v 2 = 1 state, was considered. Aims. Spectrally resolved circumstellar H2O(110-101) lines have been obtained towards three M-type AGB stars using the Odin satellite. This provides additional strong constraints on the properties of circumstellar H2O, in particular on the chemistry in the stellar atmosphere, and the photodissociation in the outer envelope. Methods. Infrared Space Observatory and Odin satellite H2O line data are used as constraints for radiative transfer models. Special consideration is taken to the spectrally resolved. Odin line profiles, and the effect of excitation to the first excited vibrational states of the stretching modes (v1 = 1 and v3 = 1) on the derived abundances is estimated. A non-local, radiative transfer code based on the accelerated lambda iteration formalism is used. A statistical analysis is performed to determine the best-fit models. Results. The H2O abundance estimates are in agreement with previous estimates. The inclusion of the Odin data sets stronger constraints on the size of the H2O envelope. The H 2O(110-101) line profiles require a significant reduction in expansion velocity compared to the terminal gas expansion velocity determined in models of CO radio line emission, indicating that the H 2O emission lines probe a region where the wind is still being accelerated. Including the v3 = 1 state significantly lowers the estimated abundances for the low-mass-loss-rate objects. This shows the importance of detailed modelling, in particular the details of the infrared spectrum in the range 3 to 6 μm, to estimate accurate circumstellar H 2O abundances. Conclusions. Spectrally resolved circumstellar H 2O emission lines are important probes of the physics and chemistry in the inner regions of circumstellar envelopes around asymptotic giant branch stars. Predictions for H2O emission lines in the spectral range of the upcoming Herschel/HIFI mission indicate that these observations will be very important in this context. © ESO 2009.
Persistent Identifierhttp://hdl.handle.net/10722/179715
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorMaercker, Men_US
dc.contributor.authorSchöier, FLen_US
dc.contributor.authorOlofsson, Hen_US
dc.contributor.authorBergman, Pen_US
dc.contributor.authorFrisk, Uen_US
dc.contributor.authorHjalmarson, Åen_US
dc.contributor.authorJusttanont, Ken_US
dc.contributor.authorKwok, Sen_US
dc.contributor.authorLarsson, Ben_US
dc.contributor.authorOlberg, Men_US
dc.contributor.authorSandqvist, Aaen_US
dc.date.accessioned2012-12-19T10:03:11Z-
dc.date.available2012-12-19T10:03:11Z-
dc.date.issued2009en_US
dc.identifier.citationAstronomy And Astrophysics, 2009, v. 494 n. 1, p. 243-252en_US
dc.identifier.issn0004-6361en_US
dc.identifier.urihttp://hdl.handle.net/10722/179715-
dc.description.abstractContext. A detailed radiative transfer code has been previously used to model circumstellar ortho-H2O line emission towards six M-type asymptotic giant branch stars using Infrared Space Observatory Long Wavelength Spectrometer data. Collisional and radiative excitation, including the v 2 = 1 state, was considered. Aims. Spectrally resolved circumstellar H2O(110-101) lines have been obtained towards three M-type AGB stars using the Odin satellite. This provides additional strong constraints on the properties of circumstellar H2O, in particular on the chemistry in the stellar atmosphere, and the photodissociation in the outer envelope. Methods. Infrared Space Observatory and Odin satellite H2O line data are used as constraints for radiative transfer models. Special consideration is taken to the spectrally resolved. Odin line profiles, and the effect of excitation to the first excited vibrational states of the stretching modes (v1 = 1 and v3 = 1) on the derived abundances is estimated. A non-local, radiative transfer code based on the accelerated lambda iteration formalism is used. A statistical analysis is performed to determine the best-fit models. Results. The H2O abundance estimates are in agreement with previous estimates. The inclusion of the Odin data sets stronger constraints on the size of the H2O envelope. The H 2O(110-101) line profiles require a significant reduction in expansion velocity compared to the terminal gas expansion velocity determined in models of CO radio line emission, indicating that the H 2O emission lines probe a region where the wind is still being accelerated. Including the v3 = 1 state significantly lowers the estimated abundances for the low-mass-loss-rate objects. This shows the importance of detailed modelling, in particular the details of the infrared spectrum in the range 3 to 6 μm, to estimate accurate circumstellar H 2O abundances. Conclusions. Spectrally resolved circumstellar H 2O emission lines are important probes of the physics and chemistry in the inner regions of circumstellar envelopes around asymptotic giant branch stars. Predictions for H2O emission lines in the spectral range of the upcoming Herschel/HIFI mission indicate that these observations will be very important in this context. © ESO 2009.en_US
dc.languageengen_US
dc.publisherE D P Sciences. The Journal's web site is located at http://www.aanda.orgen_US
dc.relation.ispartofAstronomy and Astrophysicsen_US
dc.subjectStars: Abundancesen_US
dc.subjectStars: Agb And Post-Agben_US
dc.subjectStars: Evolutionen_US
dc.subjectStars: Mass-Lossen_US
dc.titleCircumstellar water vapour in M-type AGB stars: Constraints from H 2O(110-101) lines obtained with Odinen_US
dc.typeArticleen_US
dc.identifier.emailKwok, S: deannote@hku.hken_US
dc.identifier.authorityKwok, S=rp00716en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1051/0004-6361:200810017en_US
dc.identifier.scopuseid_2-s2.0-59549088574en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-59549088574&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume494en_US
dc.identifier.issue1en_US
dc.identifier.spage243en_US
dc.identifier.epage252en_US
dc.identifier.isiWOS:000263040200020-
dc.publisher.placeFranceen_US
dc.identifier.scopusauthoridMaercker, M=8540918100en_US
dc.identifier.scopusauthoridSchöier, FL=6603684180en_US
dc.identifier.scopusauthoridOlofsson, H=7004294995en_US
dc.identifier.scopusauthoridBergman, P=7006615192en_US
dc.identifier.scopusauthoridFrisk, U=8966521600en_US
dc.identifier.scopusauthoridHjalmarson, Å=15744175200en_US
dc.identifier.scopusauthoridJusttanont, K=6701597318en_US
dc.identifier.scopusauthoridKwok, S=22980498300en_US
dc.identifier.scopusauthoridLarsson, B=7202678664en_US
dc.identifier.scopusauthoridOlberg, M=16201342800en_US
dc.identifier.scopusauthoridSandqvist, Aa=35451841800en_US

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