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Article: Maser properties of the enigmatic IRAS source 19312+1950

TitleMaser properties of the enigmatic IRAS source 19312+1950
Authors
KeywordsCircumstellar matter
ISM: jets and outflows
Masers
Stars: imaging
Stars: individual (IRAS 19312+1950)
Issue Date2011
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 2011, v. 728 n. 2 How to Cite?
AbstractThe IRAS source, 19312+1950, exhibits SiO maser emission, which is predominantly detected in evolved stars enshrouded by a cold molecular envelope. In fact, the majority of the observational properties of IRAS 19312+1950 are consistent with the nature of an asymptotic giant branch (AGB) star or post-AGB star. Interestingly, however, some of the observational properties cannot be readily explained within the standard scheme of stellar evolution, and those are rather reminiscent of young stellar objects. In the present research, we considered the evolutionary status of IRAS 19312+1950 as revealed by the very long baseline interferometry and MERLIN observations in SiO, H 2O, and OH maser lines. The double-peaked profile of the 22 GHz H 2O maser line is clearly detected, with the emission regions of its redshifted and blueshifted components separately located, leaving a space of about 10.9 mas between them. The kinematic properties of the H 2O maser emission region appear to be more consistent with a bipolar flow rather than other interpretations such as the Keplerian rotation of a disk. The redshifted component of the SiO maser emission, which exhibits a double-peak profile in previous single-dish observations, is clearly detected in the present interferometry, while the 1612 MHz OH maser line exhibits a complicated line profile consisting of a single strong peak and many weak, high-velocity spikes. The structure of the OH maser emission region is partially resolved, and the kinematic properties of the OH maser emission region are observations reminiscent of a spherically expanding shell, even though the evidence is scant. Collectively, the maser observations described here provide additional support for the evolved star hypothesis for IRAS 19312+1950. © 2011. The American Astronomical Society.
Persistent Identifierhttp://hdl.handle.net/10722/142457
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council of Hong KongHKU 703308P
HKU 704209P
HKU 704710P
University of Hong Kong200802159006
Japan Society for the Promotion of Science18740109
20540234
Funding Information:

This work is supported by a grant awarded to J.N. from the Research Grants Council of Hong Kong (project code: HKU 703308P; HKU 704209P; HKU 704710P) and the Seed Funding Program for Basic Research of the University of Hong Kong (project code: 200802159006). H. I. and S. D. have been financially supported by Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (18740109 and 20540234, respectively). The authors thank Drs. Tom Muxlow, Anita Richards, and Peter Thomasson for supporting the observation and data reduction. The NRAO's VLBA (and HSA) is a facility of the National Science Foundation of the USA, operated under a cooperative agreement by Associated Universities, Inc. We acknowledge all staff members and students who have helped in array operation and in data correlation of the JVN in order to obtain the present archival data. J.N. thanks Yong Zhang, Chih-Hao Hsia, Bosco H. K. Yung, and Thomas K. T. Fok for stimulating discussions.

References
Grants

 

DC FieldValueLanguage
dc.contributor.authorNakashima, JIen_HK
dc.contributor.authorDeguchi, Sen_HK
dc.contributor.authorImai, Hen_HK
dc.contributor.authorKemball, Aen_HK
dc.contributor.authorLewis, BMen_HK
dc.date.accessioned2011-10-28T02:46:37Z-
dc.date.available2011-10-28T02:46:37Z-
dc.date.issued2011en_HK
dc.identifier.citationAstrophysical Journal Letters, 2011, v. 728 n. 2en_HK
dc.identifier.issn2041-8205en_HK
dc.identifier.urihttp://hdl.handle.net/10722/142457-
dc.description.abstractThe IRAS source, 19312+1950, exhibits SiO maser emission, which is predominantly detected in evolved stars enshrouded by a cold molecular envelope. In fact, the majority of the observational properties of IRAS 19312+1950 are consistent with the nature of an asymptotic giant branch (AGB) star or post-AGB star. Interestingly, however, some of the observational properties cannot be readily explained within the standard scheme of stellar evolution, and those are rather reminiscent of young stellar objects. In the present research, we considered the evolutionary status of IRAS 19312+1950 as revealed by the very long baseline interferometry and MERLIN observations in SiO, H 2O, and OH maser lines. The double-peaked profile of the 22 GHz H 2O maser line is clearly detected, with the emission regions of its redshifted and blueshifted components separately located, leaving a space of about 10.9 mas between them. The kinematic properties of the H 2O maser emission region appear to be more consistent with a bipolar flow rather than other interpretations such as the Keplerian rotation of a disk. The redshifted component of the SiO maser emission, which exhibits a double-peak profile in previous single-dish observations, is clearly detected in the present interferometry, while the 1612 MHz OH maser line exhibits a complicated line profile consisting of a single strong peak and many weak, high-velocity spikes. The structure of the OH maser emission region is partially resolved, and the kinematic properties of the OH maser emission region are observations reminiscent of a spherically expanding shell, even though the evidence is scant. Collectively, the maser observations described here provide additional support for the evolved star hypothesis for IRAS 19312+1950. © 2011. The American Astronomical Society.en_HK
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_HK
dc.relation.ispartofAstrophysical Journal Lettersen_HK
dc.rightsThe Astrophysical Journal. Copyright © Institute of Physics Publishing, Inc.en_US
dc.subjectCircumstellar matteren_HK
dc.subjectISM: jets and outflowsen_HK
dc.subjectMasersen_HK
dc.subjectStars: imagingen_HK
dc.subjectStars: individual (IRAS 19312+1950)en_HK
dc.titleMaser properties of the enigmatic IRAS source 19312+1950en_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0004-637X&volume=728&issue=2, article no. 76&spage=&epage=&date=2011&atitle=Maser+properties+of+the+Enigmatic+IRAS+Source+19312+1950en_US
dc.identifier.emailNakashima, JI: junichi@hku.hken_HK
dc.identifier.authorityNakashima, JI=rp00764en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1088/0004-637X/728/2/76en_HK
dc.identifier.scopuseid_2-s2.0-84891224982en_HK
dc.identifier.hkuros184254en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79960257169&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume728en_HK
dc.identifier.issue2en_HK
dc.identifier.isiWOS:000286973600003-
dc.publisher.placeUnited Kingdomen_HK
dc.relation.projectObservational Study of Red Supergiants Embedded in Galactic Young Open Clusters-
dc.relation.projectRadio Interferometric Observations of Post-AGB Stars and Proto-Planetary Nebulae-
dc.relation.projectSystematic Study of Circumstellar Maser Sources-
dc.identifier.scopusauthoridNakashima, JI=35485342300en_HK
dc.identifier.scopusauthoridDeguchi, S=7006314159en_HK
dc.identifier.scopusauthoridImai, H=35484255500en_HK
dc.identifier.scopusauthoridKemball, A=6602509991en_HK
dc.identifier.scopusauthoridLewis, BM=7401868009en_HK

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