Kraemer, Kathleen E. and Hora, Joseph L. and Egan, Michael P. and Adams, Joseph and Allen, Lori E. and Bontemps, Sylvain and Carey, Sean J. and Fazio, Giovanni G. and Gutermuth, Robert and Keto, Eric and Koenig, Xavier P. and Megeath, S. Thomas and Mizuno, Donald R. and Motte, Frederique and Price, Stephan D. and Schneider, Nicola and Simon, Robert and Smith, Howard A. (2010) Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region. Astronomical Journal, 139 (6). pp. 2319-2329. ISSN 0004-6256 http://resolver.caltech.edu/CaltechAUTHORS:20100608-073330165
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We present observations of newly discovered 24 μm circumstellar structures detected with MIPS around three evolved stars in the Cygnus-X star-forming region. One of the objects, BD+43 3710, has a bipolar nebula, possibly due to an outflow or a torus of material. A second, HBHA 4202-22, a Wolf-Rayet candidate, shows a circular shell of 24 μm emission suggestive of either a limb-brightened shell or disk seen face-on. No diffuse emission was detected around either of these two objects in the Spitzer 3.6-8 μm IRAC bands. The third object is the luminous blue variable candidate G79.29+0.46. We resolved the previously known inner ring in all four IRAC bands. The 24 μm emission from the inner ring extends ~1.'2 beyond the shorter wavelength emission, well beyond what can be attributed to the difference in resolutions between MIPS and IRAC. Additionally, we have discovered an outer ring of 24 μm emission, possibly due to an earlier episode of mass loss. For the two shell stars, we present the results of radiative transfer models, constraining the stellar and dust shell parameters. The shells are composed of amorphous carbon grains, plus polycyclic aromatic hydrocarbons in the case of G79.29+0.46. Both G79.29+0.46 and HBHA 4202-22 lie behind the main Cygnus-X cloud. Although G79.29+0.46 simply may be on the far side of the cloud, HBHA 4202-22 is unrelated to the Cygnus-X star formation region.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 October 7; accepted 2010 March 8; published 2010 April 23. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under NASA contract 1407. Support for this work was provided in part by NASA. This research has made use of NASA’s Astrophysics Data System Bibliographic Services, data products from 2MASS which is a joint project of the University of Massachusetts and IPAC/Caltech funded by NASA and the NSF, and the Simbad database operated at CDS, Strasbourg, France. We thank the anonymous referee for useful suggestions that improved the paper. Facilities: Spitzer(IRAC, IRS, MIPS)|
|Subject Keywords:||stars: AGB and post-AGB – stars: individual (BD+43 3710, HBHA 4202-22, G79.29−0.46)|
|Classification Code:||PACS: 97.10.Cv; 97.30.Dg; 98.38.Fs; 98.70.Qy; 98.38.Dq; 95.85.Gn|
|Official Citation:||Kathleen E. Kraemer et al 2010 The Astronomical Journal 139 2319 doi: 10.1088/0004-6256/139/6/2319|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||08 Jun 2010 15:07|
|Last Modified:||26 Dec 2012 12:07|
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