PerspectiveAstronomy

Galactic archaeology with Gaia

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Science  06 Sep 2019:
Vol. 365, Issue 6457, pp. 979-980
DOI: 10.1126/science.aay0628

Summary

The past and present merger activity of the Milky Way galaxy has recently been put into sharp focus through the analysis of data from the Gaia astrometric satellite. These data were released by the European Space Agency in 2016 (DR1) and 2018 (DR2). The emerging picture created is one of persistent disequilibrium, with high merger activity some 10 billion years ago that plausibly created the stellar halo and thick disk (see the figure), followed by a lull during which only lower-mass satellite galaxies were accreted. The Milky Way is now acquiring the Sagittarius dwarf galaxy, which is likely sculpting the galaxy's thin disk.

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