Constraints on the Proper Motion of the Andromeda Galaxy Based on the Survival of Its Satellite M33

  title={Constraints on the Proper Motion of the Andromeda Galaxy Based on the Survival of Its Satellite M33},
  author={Abraham Loeb and Mark J. Reid and Andreas Brunthaler and Heino Falcke},
  journal={The Astrophysical Journal},
  pages={894 - 898}
A major uncertainty in the dynamical history of the Local Group of galaxies originates from the unknown transverse speed of the Andromeda galaxy (M31) relative to the Milky Way. We show that the recent VLBA measurement of the proper motion of Andromeda's satellite, M33, severely constrains the possible values of M31's proper motion. The condition that M33's stellar disk has not been tidally disrupted by either M31 or the Milky Way over the past 10 billion years favors a proper motion amplitude… 

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