The Local Density of Halo Giants

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

[43.05] The Local Density of Halo Giants

H. Morrison (NOAO)

A new estimate of the local density of halo giants is presented. This estimate is derived from an objective-prism survey for nearby metal-weak stars, and so is free from many of the assumptions needed to derive the local halo density in the traditional way, from high proper motion surveys. The number agrees well with estimates of the local density of halo horizontal-branch stars, but is approximately a factor of 2 smaller than the density derived by Bahcall and Casertano (1986). This may be due to the inclusion of some thick disk stars in their proper-motion selected sample. Using the new local density estimate, a simple model is built to predict numbers of halo giants in specified directions in the Galaxy. It is shown that it performs much better than the Bahcall-Soniera model, in the specific case of halo giants.

Wednesday program listing