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 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 ~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.
Original language | English (US) |
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Pages (from-to) | L5-L9 |
Journal | Monthly Notices of the Royal Astronomical Society: Letters |
Volume | 401 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2010 |
Keywords
- Cosmology: theory
- Galaxies: evolution
- Galaxies: stellar content
- Stars: formation
- Stars: population II
- Supernovae: general
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science