Revealing evolved massive stars with Spitzer
Sep, 20096 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 405 (2010) 1047
e-Print:
- 0909.0458 [astro-ph.SR]
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Abstract: (arXiv)
Massive evolved stars loss a large fraction of their mass via copious stellar wind or instant outbursts and during certain evolutionary phases they can be identified via the presence of their circumstellar nebulae. In this Letter, we present the results of search for ring-like and bipolar nebulae (reminiscent of circumstellar nebulae around evolved massive stars) using archival 24 m data obtained with the Multiband Imaging Photometer for Spitzer. We discovered 94 nebulae and suggest that they could serve as indicators that their central stars are Luminous Blue Variables (LBVs) or related evolved stars. Our suggestion is supported by spectroscopic follow-ups of two dozens of central stars associated with the nebulae from our sample, most of which turns out to be either candidate LBVs (cLBVs), late WN-type (WNL) Wolf-Rayet (WR) stars or blue supergiants. We expect that the forthcoming spectroscopy of the remaining objects from our list, accompanied by the spectrophotometric monitoring of the already discovered cLBVs, will further increase the known population of Galactic LBVs, which in turn would have profound consequences for better understanding the LBV phenomenon and its role in the transition between hydrogen burning O stars and helium burning WR stars. We also report the detection of an arc-like structure attached to the cLBV HD 326823 and extended diffuse emission associated with the previously known shells around the cLBV GAL 079.29+00.46 and the WN8h star WR 124.References(52)
Figures(8)