THE M31 VELOCITY VECTOR. II. RADIAL ORBIT TOWARD THE MILKY WAY AND IMPLIED LOCAL GROUP MASS

@article{vanderMarel2012THEMV,
  title={THE M31 VELOCITY VECTOR. II. RADIAL ORBIT TOWARD THE MILKY WAY AND IMPLIED LOCAL GROUP MASS},
  author={Roeland P. van der Marel and Mark A. Fardal and Gurtina Besla and Rachael L. Beaton and Sangmo Tony Sohn and Jay Anderson and Tom Brown and Puragra Guhathakurta},
  journal={The Astrophysical Journal},
  year={2012},
  volume={753}
}
We determine the velocity vector of M31 with respect to the Milky Way and use this to constrain the mass of the Local Group, based on Hubble Space Telescope proper-motion measurements of three fields presented in Paper I. We construct N-body models for M31 to correct the measurements for the contributions from stellar motions internal to M31. This yields an unbiased estimate for the M31 center-of-mass motion. We also estimate the center-of-mass motion independently, using the kinematics of… 

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