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Article: Dense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420
Title | Dense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420 |
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Authors | |
Keywords | circumstellar matter radiative transfer stars: mass-loss supergiants |
Issue Date | 2017 |
Publisher | American 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? |
Abstract | The 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 Identifier | http://hdl.handle.net/10722/250558 |
ISSN | 2023 Impact Factor: 4.8 2023 SCImago Journal Rankings: 1.905 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Dinh-V-Trung, DVT | - |
dc.contributor.author | Wong, KT | - |
dc.contributor.author | Lim, JJL | - |
dc.date.accessioned | 2018-01-18T04:28:58Z | - |
dc.date.available | 2018-01-18T04:28:58Z | - |
dc.date.issued | 2017 | - |
dc.identifier.citation | The Astrophysical Journal, 2017, v. 851 n. 1, p. 65:1-14 | - |
dc.identifier.issn | 0004-637X | - |
dc.identifier.uri | http://hdl.handle.net/10722/250558 | - |
dc.description.abstract | The 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.language | eng | - |
dc.publisher | American 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.ispartof | The Astrophysical Journal | - |
dc.rights | The Astrophysical Journal. Copyright © American Astronomical Society, co-published with Institute of Physics Publishing, Inc. | - |
dc.subject | circumstellar matter | - |
dc.subject | radiative transfer | - |
dc.subject | stars: mass-loss | - |
dc.subject | supergiants | - |
dc.title | Dense Molecular Clumps in the Envelope of the Yellow Hypergiant IRC+10420 | - |
dc.type | Article | - |
dc.identifier.email | Lim, JJL: jjlim@hku.hk | - |
dc.identifier.authority | Lim, JJL=rp00745 | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.3847/1538-4357/aa932b | - |
dc.identifier.scopus | eid_2-s2.0-85038623070 | - |
dc.identifier.hkuros | 283995 | - |
dc.identifier.volume | 851 | - |
dc.identifier.issue | 1 | - |
dc.identifier.spage | 65:1 | - |
dc.identifier.epage | 14 | - |
dc.identifier.isi | WOS:000417907200014 | - |
dc.publisher.place | United States | - |
dc.identifier.issnl | 0004-637X | - |