Metal-Rich Stars In The Galactic Halo ?

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Session 43 -- Galactic Structure
Display presentation, Wednesday, 9:20-6:30, Pauley Room

[43.06] Metal-Rich Stars In The Galactic Halo ?

G. Bazan (McDonald Observatory), C. Sneden (U. of Texas), K. M. Yoss (U. of Illinois)

We have obtained high-resolution spectra of and have performed abundance analyses on dwarfs and giants of the galactic halo that, by previous estimates, seem to be metal-rich ([Fe/H] > -1.0). Under the theory of galaxy formation espoused by Eggen, Lynden-Bell, and Sandage (1962), star formation and chemical enrichment in the galactic halo should have ceased by the point where [Fe/H] = -1.0. The existence of these stars as genuine halo objects presents a severe challenge to this interpretation of galaxy formation. The dwarfs in our sample have been taken from the Carney and Latham (1987, Astron. J., 93, 116) compilation using a kinematical criterion for halo membership (V < -150 km/sec). Program giants have been taken from North Galactic Pole observations by Yoss et al. (1987, Astron. J., 94, 1600.) with heights above the plane of z > 1.5 kpc. Initial abundance analyses of these stars show that they are indeed metal-rich and further abundance ratio analyses will indicate possible scenarios for their presence in the halo.

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