Halpha Emission Line Stars in M31, M33 and Seven Local Group Dwarfs
Abstract
While there are many ideas as to how differing galactic environments affect the formation and evolution of massive stars, the numbers of stars with known physical properties outside the Milky Way are too scarce to provide much insight. For instance, we have a very poor idea as to the actual number of Luminous Blue Variables (LBVs) in nearby galaxies, since these have mostly been found on the basis of strong photometric variability over a span of a few decades. But, we know that the Galactic LBVs P Cygni and Eta Car had their last major photometric upsets centuries ago. Were these stars located in a nearby galaxy, we might well be unaware of them. In order to help rectify this situation, we have used the recent UBVRI catalogs of M31 and M33 (Massey et al. 2006) and seven dwarf galaxies in the Local Group (Massey et al. 2007) in conjunction with data from narrowband filters centered on Halpha, [SII] and [OIII] to select Halpha emission sources with similar characteristics to the known LBVs. This search uncovered over 300 potential Halpha emission sources in M31 and M33, and 41 potential Halpha emission sources in the dwarf galaxies. Many of the most promising objects in M31 and M33 were observed spectroscopically at WIYN in September, revealing a wealth of new LBVs and Wolf-Rayet stars. In our poster we will outline our selection method and show some of the newly found emission-lined stars.
Funding provided by the NSF through grant number AST-0453611.- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AAS...209.2702M