Mining the Galactic halo for very metal-poor stars

作者：Salvadori S^*; Ferrara A; Schneider R; Scannapieco E; Kawata D

来源：Monthly Notices of the Royal Astronomical Society, 2010, 401(1): L5-L9.

DOI：10.1111/j.1745-3933.2009.00772.x

• stars: formation
• stars: Population II
• supernovae: general
• galaxies: evolution
• galaxies: stellar content
• cosmology: theory

We study the age and metallicity distribution 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 per cent within 7 < r < 20 kpc up to >= 40 per cent 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 similar to 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.

• 出版日期2010-1-1