Abstract
Stellar Dynamics![Figure][1] Some fast-moving stars in our Milky Way Galaxy came from nearby dwarf galaxies. CREDIT: NASA/JPL-CALTECH/R. HURT (SSC/CALTECH) Dynamical interactions and supernovae can accelerate stars to high velocities, sometimes even fast enough that they are no longer gravitationally bound to their host galaxy and escape from it. Marchetti et al. have combined astrometric data with radial velocity measurements to determine the three-dimensional motions of 7 million stars within the Milky Way Galaxy. Within that sample, they identify 20 stars that are not bound to the Galaxy. Only seven of them are moving away from the Milky Way's disc; 13 stars originated elsewhere. The authors postulate that these apparently extragalactic stars may have been ejected or tidally stripped from nearby dwarf galaxies. Mon. Not. R. Astron. Soc. 10.1093/mnras/sty2592 (2018). [1]: pending:yes
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