On the early evolution of the Galactic Halo

Abstract

It is shown that the low metallicity tail of the stellar metallicity distribution predicted by simple Outflow models for the Milky Way halo depends sensitively on whether Instantaneous Recycling is adopted or relaxed. In both cases, current - and still preliminary - data suggest a ``G-dwarf problem'' for the halo (reminiscent of the local disk). We suggest that the problem can be solved by introducing a (physically motivated) early infall phase. We point out several important implications of such a modification, concerning: the putative Pop. III (super)massive stars, the number of stars expected at very low metallicities, the questions of primary nitrogen and of the dispersion in abundance ratios of halo stars.

arXiv commentAstronomy and Astrophysics, accepted for publication (5 pages, 1 fig.)

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• Multi-Element Abundance Measurements from Medium-Resolution Spectra. I. The Sculptor Dwarf Spheroidal Galaxy
• The stellar content of the Hamburg/ESO survey. V. The metallicity distribution function of the Galactic halo
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• Metal-Poor Stars and the Chemical Enrichment of the Universe
• The metallicity distribution of the halo and the satellites of the Milky way in the hierarchical merging paradigm
• HST Photometry for the Halo Stars in the Leo Elliptical NGC 3377
• The stellar content of the Hamburg/ESO survey VI. The metallicity distribution of main-sequence turnoff stars in the Galactic halo
• An Introduction to Galactic Chemical Evolution
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• The energetics, evolution, and stellar depletion of Li6 in the early Galaxy
• Modelling the chemical evolution of the Galaxy halo
• Rapidly rotating Population III stellar models as a source of primary nitrogen
• A Two-Phase Chemical Enrichment Model for the Milky Way Globular Cluster System
• Early-Age Evolution of the Milky Way Related by Extremely Metal-Poor Stars
• The G-dwarf problem in the Galaxy
• The early phases of Milky Way's chemical evolution
• The effects of population III stars on the chemical and photometrical evolution of ellipticals
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• Modelling the chemical evolution of the Milky Way