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K.S. Bjorkman, J.P. Wisniewski (U. Toledo)
Classical Be stars are rapidly rotating massive stars with circumstellar disks and emission line spectra. They are distinct from the more slowly rotating ``normal'' B stars, which do not have evidence of disks and show only absorption line spectra. While rotation is likely the dominant factor to explain this difference, the mechanism for disk formation is not well understood. Recent studies have suggested that either age (evolutionary stage) or metallicity, or both, also may play key roles in promoting the formation of disks. We have set out to test these suggestions observationally. We have observed 17 associations in the LMC, SMC, and MWG using B, V, R, and H\alpha photometry. From 2-color diagrams, we have identified roughly 600 candidate B-type emission line objects in these fields. Our preliminary results seem to contradict the suggestion that the Be phenomenon occurs in the mid- to later-half of the main-sequence. We explore the limitations of the 2-color diagram technique and discuss methods to lessen the observational biases. Optical photometry of a sample of candidate extragalactic Herbig AeBe (HAeBe) pre-main-sequence stars will also be discussed. These data show that 9 of 12 observed objects display properties which support their classification as HAeBe stars.
We acknowledge support provided by a NASA LTSA grant (NAG5-8054) and a Research Corporation Cottrell Scholar Award to KSB, and by a NASA GSRP fellowship (NGT5-50469) to JPW.
The author(s) of this abstract have provided an email address for comments about the abstract: karen@astro.utoledo.edu
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.