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arXiv · 0908.4279

Mining the Galactic Halo for Very Metal-Poor Stars

S. Salvadori·A. Ferrara·R. Schneider·E. Scannapieco·D. Kawata
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Abstract

We study the age and metallicity distribution function (MDF) of metal-poor stars in the Milky Way halo as a function of galactocentric radius by combining N-body simulations and semi-analytical methods. We find that the oldest stars populate the innermost region, while extremely metal-poor stars are more concentrated within r < 60 kpc. The MDF of [Fe/H] < -2 stars varies only very weakly within the central 50 kpc, while the relative contribution of [Fe/H] < -2 stars strongly increases with r, varying from 16% within 7 kpc < r < 20 kpc up to > 40% for r > 20 kpc. This is due to the faster descent of the spatial distribution (as seen from Earth) of the more enriched population. This implies that the outer halo < 40 kpc is the best region to search for very metal-poor stars. Beyond ~ 60 kpc the density of [Fe/H] < -2 stars is maximum within dwarf galaxies. All these features are imprinted by a combination of (i) the virialization epoch of the star-forming haloes, and (ii) the metal enrichment history of the Milky Way environment.

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S. Salvadori, A. Ferrara, R. Schneider, E. Scannapieco, D. Kawata. 2010-01-25. Mining the Galactic Halo for Very Metal-Poor Stars. https://doi.org/10.1111/j.1745-3933.2009.00772.x

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