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Stellar populations of the Milky Way halo

Paula Jofre Pfeil (MPA Garching)

This study is about stellar populations of the Milky Way halo and is about to be submitted as my PhD thesis. We want to attack the problem of age-determination for halo field stars, where the distance is not known and classical age-dating techniques are not feasible. Our alternative is to use the turn-off stars, which can be found by looking at the hottest stars of a population with a given metallicity.

Metallicities and temperatures of halo field stars are determined from the spectra of the SEGUE stars. This is done with a novel and independent method, called MAX, which compresses the spectra allowing an extremely quick parameter determination.

We found finally ages for the halo of 12-13 Gyr, based on interesting similitudes between field and globular clusters stars.