The age structure of the Milky Way's halo

Research Associate Pavel Denisenkov was among a team that generated an age map of the halo of our Galaxy, as reported today in the journal Nature Physics. The new results are based on their models of horizontal-branch (HB) stars and built an HB population synthesis tool to simulate HB color distributions for different input parameters. Comparing the mean colours of synthetic HB stars with those derived for blue HB stars in the Milky Way's halo from the Sloan Digital Sky Survey, the team has estimated the radial age gradient in the halo of our Galaxy (-25 Myr/kpc). The obtained halo age map also exhibits numerous debris streams, including the well-known Sagittarius Stream, left from the processes of merging of dwarf galaxies with the Milky Way.

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