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Article: Dense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420

TitleDense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420
Authors
Keywordscircumstellar matter
radiative transfer
stars: mass-loss
supergiants
Issue Date2017
PublisherAmerican Astronomical Society, co-published with Institute of Physics Publishing, Inc. The Journal's web site is located at http://iopscience.iop.org/0004-637X/
Citation
The Astrophysical Journal, 2017, v. 851 n. 1, p. 65:1-14 How to Cite?
AbstractThe circumstellar envelope of the hypergiant star IRC+10420 has been traced as far out in 28SiO (J = 2-1) as in 12CO J = 1-0 and 12CO J=2-1, in dramatic contrast with the centrally condensed (thermal) SiO- but extended CO-emitting envelopes of giant and supergiant stars. We present an observation of the circumstellar envelope in 28SiO (J = 1 - 0) that, when combined with the previous observation in 28SiO (J = 2 - 1), provides more stringent constraints on the density of the SiO-emitting gas than hitherto possible. The emission in 28SiO (J = 1-0) peaks at a radius of ∼2″ whereas that in 28SiO (J = 2-1) peaks at a smaller radius of ∼1″, giving rise to its ring-like appearance. The ratio of brightness temperature between 28SiO (J = 2-1) and 28SiO (J = 1-0) decreases from a value well above unity at the innermost measurable radius to about unity at a radius of ∼2″, beyond which this ratio remains approximately constant. Dividing the envelope into three zones as in models for the 12CO J = 1-0 and 12CO J = 2Dinh-1 emissions, we show that the density of the SiO-emitting gas is comparable with that of the CO-emitting gas in the inner zone but is at least an order of magnitude higher by comparison in both the middle and the outer zones. The SiO-emitting gas therefore originates from dense clumps, likely associated with the dust clumps seen in scattered optical light, surrounded by more diffuse CO-emitting interclump gas. We suggest that SiO molecules are released from dust grains due to shock interactions between the dense SiO-emitting clumps and the diffuse CO-emitting interclump gas.
Persistent Identifierhttp://hdl.handle.net/10722/250558
ISSN
2015 Impact Factor: 5.909
2015 SCImago Journal Rankings: 3.266

 

DC FieldValueLanguage
dc.contributor.authorDinh-V-Trung, DVT-
dc.contributor.authorWong, KT-
dc.contributor.authorLim, JJL-
dc.date.accessioned2018-01-18T04:28:58Z-
dc.date.available2018-01-18T04:28:58Z-
dc.date.issued2017-
dc.identifier.citationThe Astrophysical Journal, 2017, v. 851 n. 1, p. 65:1-14-
dc.identifier.issn0004-637X-
dc.identifier.urihttp://hdl.handle.net/10722/250558-
dc.description.abstractThe circumstellar envelope of the hypergiant star IRC+10420 has been traced as far out in 28SiO (J = 2-1) as in 12CO J = 1-0 and 12CO J=2-1, in dramatic contrast with the centrally condensed (thermal) SiO- but extended CO-emitting envelopes of giant and supergiant stars. We present an observation of the circumstellar envelope in 28SiO (J = 1 - 0) that, when combined with the previous observation in 28SiO (J = 2 - 1), provides more stringent constraints on the density of the SiO-emitting gas than hitherto possible. The emission in 28SiO (J = 1-0) peaks at a radius of ∼2″ whereas that in 28SiO (J = 2-1) peaks at a smaller radius of ∼1″, giving rise to its ring-like appearance. The ratio of brightness temperature between 28SiO (J = 2-1) and 28SiO (J = 1-0) decreases from a value well above unity at the innermost measurable radius to about unity at a radius of ∼2″, beyond which this ratio remains approximately constant. Dividing the envelope into three zones as in models for the 12CO J = 1-0 and 12CO J = 2Dinh-1 emissions, we show that the density of the SiO-emitting gas is comparable with that of the CO-emitting gas in the inner zone but is at least an order of magnitude higher by comparison in both the middle and the outer zones. The SiO-emitting gas therefore originates from dense clumps, likely associated with the dust clumps seen in scattered optical light, surrounded by more diffuse CO-emitting interclump gas. We suggest that SiO molecules are released from dust grains due to shock interactions between the dense SiO-emitting clumps and the diffuse CO-emitting interclump gas.-
dc.languageeng-
dc.publisherAmerican Astronomical Society, co-published with Institute of Physics Publishing, Inc. The Journal's web site is located at http://iopscience.iop.org/0004-637X/-
dc.relation.ispartofThe Astrophysical Journal-
dc.rightsThe Astrophysical Journal. Copyright © American Astronomical Society, co-published with Institute of Physics Publishing, Inc.-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subjectcircumstellar matter-
dc.subjectradiative transfer-
dc.subjectstars: mass-loss-
dc.subjectsupergiants-
dc.titleDense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420-
dc.typeArticle-
dc.identifier.emailLim, JJL: jjlim@hku.hk-
dc.identifier.authorityLim, JJL=rp00745-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.3847/1538-4357/aa932b-
dc.identifier.scopuseid_2-s2.0-85038623070-
dc.identifier.hkuros283995-
dc.identifier.volume851-
dc.identifier.issue1-
dc.identifier.spage65:1-
dc.identifier.epage14-
dc.publisher.placeUnited States-

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