Magnesium Isotopes in Halo Stars

Abstract

We have determined Mg isotope ratios in halo field dwarfs and giants in the globular cluster M71 based on high S/N high spectral resolution (R = 10${}^5$) Keck HIRES spectra. Unlike previous claims of an important contribution from intermediate-mass AGB stars to the Galactic halo, we find that our ${}^{26}$Mg/${}^{24}$Mg ratios can be explained by massive stars.

Proceedings, First Stars III, July 16-20, 2007, Santa Fe