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Article: First detection of CO lines in a water fountain star

TitleFirst detection of CO lines in a water fountain star
Authors
KeywordsRadio lines: stars
Stars: AGB and post-AGB
Stars: circumstellar matter
Stars: evolution
Stars: individual: IRAS16342-3814
Stars: winds, outflows
Issue Date2008
PublisherE D P Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy And Astrophysics, 2008, v. 488 n. 2, p. L21-L24 How to Cite?
AbstractContext: Water fountain stars are very young post-AGB stars with high velocity water maser jets. They are the best objects in which to study the onset of bipolar jets from evolved stars due to their young dynamical ages. However, none of them has been observed in any thermal lines. Aims: We aim to search for CO lines in the water fountain star IRAS16342-3814 and investigate the properties of its thermal gas. Methods: The proximity, peculiar stellar velocity and high Galactic latitude of IRAS16342-3814 make a single dish observation possible. We use the Arizona Radio Observatory 10m telescope to observe the CO?=2-1 line and compare the line parameters with those of masers. Results: We report the detection of CO and CO?=2-1 lines from IRAS16342-3814. The inferred CO mass loss rate is an order of magnitude lower than the infrared and OH mass loss rates, indicating a very cold and thick O-rich circumstellar envelope around the star. We also find a CO expansion velocity of = 46 1kms that is too high for an AGB wind and confirm the systemic velocity of 441 kms. In addition we measure a very low CO/CO line ratio of 1.7. Conclusions: The first detection of CO lines has provided a new way to investigate water fountain stars. Given the high expansion velocity of the CO gas and its relation to maser velocities, we infer that the CO emission region is co-located with the OH mainline masers in the warm base of the optical bipolar lobes, while the high velocity OH1612MHz and HO masers are located in the side walls and at the farthest ends of the bipolar lobes, respectively. Further observations are highly desirable to understand the very low CO/CO line ratio. © 2008 ESO.
Persistent Identifierhttp://hdl.handle.net/10722/59578
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446
ISI Accession Number ID
Funding AgencyGrant Number
National Natural Science Foundation of China10433030
10503011
NSCNSC 96-2112-M-001-018-MY3
Funding Information:

We thank ARO telescope operators for the assistance in remote observations. J.H. acknowledge the projects Nos. 10433030 and 10503011 of the National Natural Science Foundation of China. T. I. acknowledges the support from NSC grant NSC 96-2112-M-001-018-MY3. The SMT is operated by the Arizona Radio Observatory (ARO), Steward Observatory, University of Arizona.

References

 

DC FieldValueLanguage
dc.contributor.authorHe, JHen_HK
dc.contributor.authorImai, Hen_HK
dc.contributor.authorHasegawa, TIen_HK
dc.contributor.authorCampbell, SWen_HK
dc.contributor.authorNakashima, Jen_HK
dc.date.accessioned2010-05-31T03:53:08Z-
dc.date.available2010-05-31T03:53:08Z-
dc.date.issued2008en_HK
dc.identifier.citationAstronomy And Astrophysics, 2008, v. 488 n. 2, p. L21-L24en_HK
dc.identifier.issn0004-6361en_HK
dc.identifier.urihttp://hdl.handle.net/10722/59578-
dc.description.abstractContext: Water fountain stars are very young post-AGB stars with high velocity water maser jets. They are the best objects in which to study the onset of bipolar jets from evolved stars due to their young dynamical ages. However, none of them has been observed in any thermal lines. Aims: We aim to search for CO lines in the water fountain star IRAS16342-3814 and investigate the properties of its thermal gas. Methods: The proximity, peculiar stellar velocity and high Galactic latitude of IRAS16342-3814 make a single dish observation possible. We use the Arizona Radio Observatory 10m telescope to observe the CO?=2-1 line and compare the line parameters with those of masers. Results: We report the detection of CO and CO?=2-1 lines from IRAS16342-3814. The inferred CO mass loss rate is an order of magnitude lower than the infrared and OH mass loss rates, indicating a very cold and thick O-rich circumstellar envelope around the star. We also find a CO expansion velocity of = 46 1kms that is too high for an AGB wind and confirm the systemic velocity of 441 kms. In addition we measure a very low CO/CO line ratio of 1.7. Conclusions: The first detection of CO lines has provided a new way to investigate water fountain stars. Given the high expansion velocity of the CO gas and its relation to maser velocities, we infer that the CO emission region is co-located with the OH mainline masers in the warm base of the optical bipolar lobes, while the high velocity OH1612MHz and HO masers are located in the side walls and at the farthest ends of the bipolar lobes, respectively. Further observations are highly desirable to understand the very low CO/CO line ratio. © 2008 ESO.en_HK
dc.languageengen_HK
dc.publisherE D P Sciences. The Journal's web site is located at http://www.aanda.orgen_HK
dc.relation.ispartofAstronomy and Astrophysicsen_HK
dc.subjectRadio lines: starsen_HK
dc.subjectStars: AGB and post-AGBen_HK
dc.subjectStars: circumstellar matteren_HK
dc.subjectStars: evolutionen_HK
dc.subjectStars: individual: IRAS16342-3814en_HK
dc.subjectStars: winds, outflowsen_HK
dc.titleFirst detection of CO lines in a water fountain staren_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0004-6361&volume=488&spage=L21&epage=L24&date=2008&atitle=First+detection+of+CO+lines+in+a+water+fountain+staren_HK
dc.identifier.emailNakashima, J: junichi@hku.hken_HK
dc.identifier.authorityNakashima, J=rp00764en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1051/0004-6361:200810303en_HK
dc.identifier.scopuseid_2-s2.0-50549085138en_HK
dc.identifier.hkuros152874en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-50549085138&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume488en_HK
dc.identifier.issue2en_HK
dc.identifier.spageL21en_HK
dc.identifier.epageL24en_HK
dc.identifier.isiWOS:000258760300003-
dc.publisher.placeFranceen_HK
dc.identifier.scopusauthoridHe, JH=7404983818en_HK
dc.identifier.scopusauthoridImai, H=35484255500en_HK
dc.identifier.scopusauthoridHasegawa, TI=7404173711en_HK
dc.identifier.scopusauthoridCampbell, SW=8071690500en_HK
dc.identifier.scopusauthoridNakashima, J=35485342300en_HK

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