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Article: IRAS 22272+5435 - A source with 30 and 21 μm features

TitleIRAS 22272+5435 - A source with 30 and 21 μm features
Authors
KeywordsCircumstellar Matter
Infrared: Stars
Stars: Agb, Post-Agb
Stars: Individual: Iras 22272+5435
Issue Date1997
PublisherE D P Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy And Astrophysics, 1997, v. 317 n. 3, p. 859-870 How to Cite?
AbstractRecent observations have shown that IRAS 22272+ 5435, a post-AGB object with a cool central star, is one of the few sources known which displays strong 21 and 30 μm features. We present a detailed analysis of the spectral energy distribution and discuss the possible nature of the dust grains in the circumstellar envelope around this source. We find that grains of pure magnesium sulfides could be responsible for the observed 30 μm feature provided they have a high enough temperature and an appropriate broad distribution of shapes inside the shell. The absorption properties of such grains at optical and ultraviolet wavelengths are unknown, so at the present time we are unable to estimate how high a temperature they would have in the circumstellar shell; laboratory measurements of the the optical properties are needed. The 30 μm feature cannot be produced by mantles of magnesium sulfide covering an amorphous carbon core as such grains are shown to have two maxima in their absorption cross sections around a minimum at about 30 μm. Since the material(s) responsible for 21 and 30 μm features is (are) still unknown we constructed an empirical opacity function which provides a reasonable fit to the energy distribution at far-infrared wavelengths. We also show that small particles (with radii smaller than 10 Å) having properties very similar to those of PAH molecules are an indispensable part of dust around this source. For these small grains the quantum treatment of heating and cooling processes is important. Assuming that the central star of IRAS 22272+5435 is burning H quiescently in a shell, the parameters of the best fit to the energy distribution of this source indicate a stellar core mass 0.60 M ⊙ which is presently evolving with no (or with very little) mass loss.
Persistent Identifierhttp://hdl.handle.net/10722/179634
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446
References

 

DC FieldValueLanguage
dc.contributor.authorSzczerba, Ren_US
dc.contributor.authorOmont, Aen_US
dc.contributor.authorVolk, Ken_US
dc.contributor.authorCox, Pen_US
dc.contributor.authorKwok, Sen_US
dc.date.accessioned2012-12-19T10:02:11Z-
dc.date.available2012-12-19T10:02:11Z-
dc.date.issued1997en_US
dc.identifier.citationAstronomy And Astrophysics, 1997, v. 317 n. 3, p. 859-870en_US
dc.identifier.issn0004-6361en_US
dc.identifier.urihttp://hdl.handle.net/10722/179634-
dc.description.abstractRecent observations have shown that IRAS 22272+ 5435, a post-AGB object with a cool central star, is one of the few sources known which displays strong 21 and 30 μm features. We present a detailed analysis of the spectral energy distribution and discuss the possible nature of the dust grains in the circumstellar envelope around this source. We find that grains of pure magnesium sulfides could be responsible for the observed 30 μm feature provided they have a high enough temperature and an appropriate broad distribution of shapes inside the shell. The absorption properties of such grains at optical and ultraviolet wavelengths are unknown, so at the present time we are unable to estimate how high a temperature they would have in the circumstellar shell; laboratory measurements of the the optical properties are needed. The 30 μm feature cannot be produced by mantles of magnesium sulfide covering an amorphous carbon core as such grains are shown to have two maxima in their absorption cross sections around a minimum at about 30 μm. Since the material(s) responsible for 21 and 30 μm features is (are) still unknown we constructed an empirical opacity function which provides a reasonable fit to the energy distribution at far-infrared wavelengths. We also show that small particles (with radii smaller than 10 Å) having properties very similar to those of PAH molecules are an indispensable part of dust around this source. For these small grains the quantum treatment of heating and cooling processes is important. Assuming that the central star of IRAS 22272+5435 is burning H quiescently in a shell, the parameters of the best fit to the energy distribution of this source indicate a stellar core mass 0.60 M ⊙ which is presently evolving with no (or with very little) mass loss.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.subjectCircumstellar Matteren_US
dc.subjectInfrared: Starsen_US
dc.subjectStars: Agb, Post-Agben_US
dc.subjectStars: Individual: Iras 22272+5435en_US
dc.titleIRAS 22272+5435 - A source with 30 and 21 μm featuresen_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.scopuseid_2-s2.0-0000485235en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0000485235&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume317en_US
dc.identifier.issue3en_US
dc.identifier.spage859en_US
dc.identifier.epage870en_US
dc.publisher.placeFranceen_US
dc.identifier.scopusauthoridSzczerba, R=7004424914en_US
dc.identifier.scopusauthoridOmont, A=7007143431en_US
dc.identifier.scopusauthoridVolk, K=7006571965en_US
dc.identifier.scopusauthoridCox, P=44561017600en_US
dc.identifier.scopusauthoridKwok, S=22980498300en_US

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