Origin of the Peculiar Galactic Center He\thinspace{\sc I} Stars

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Session 66 -- Galactic Center
Oral presentation, Tuesday, 10, 1995, 2:00pm - 3:30pm

[66.03D] Origin of the Peculiar Galactic Center He\thinspace{\sc I} Stars

P.~Tamblyn, G.~H.~Rieke, \& F.~Melia (Steward Observatory)

\newcommand{\hei}{He\,{\sc I}} \newcommand{\sgrastar}{Sgr~A$^*$}

We show that blue stars are present at the Galactic Center (GC) in numbers that are incompatible with normal stellar evolution. \hei\ 2.058\,\micron\ images with a spatial resolution of 1\arcsec\ show that the \hei\ emission is concentrated on point sources, most of which are bright in the infrared, indicating they are warm and very luminous. Comparison with Monte Carlo stellar population models demonstrates that normal evolution is incapable of producing this population. Near-infrared spectroscopy at high angular and spectral resolution has been obtained, along with spectra of an extensive suite of other warm, luminous stars. The spectral comparisons confirm the peculiarity of the GC stars. Constraints from space-based observations on the blue light associated with nuclear populations in nearby galaxies demonstrate that the GC is unique or in a time dependent phase. We have developed a model which shows that the concentration of distinctive stars in the GC could result from stellar collisions of red supergiants with low mass stars or stellar remnants. These interactions cause the supergiants from a recent star formation event to lose their envelopes prematurely. This model predicts similar populations of peculiar stars only in other galactic nuclei which have undergone recent star formation.

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