Fading Features Found in the Kinematics of the Far-Reaching Milky Way
  Stellar Halo
  We test the long-term kinematical stability of a Galactic stellar halo model,
due to Kafle, et al. (2012), who study the kinematics of approximately 5000
blue horizontal branch (BHB) stars in the Sloan Digital Sky Survey (SDSS). The
velocity dispersion $\sigma$ and anisotropy parameter $\beta$ of the stars have
been determined as functions of Galactocentric radius, over the range
$6<R_\mathrm{GC} < 25$ kpc, and show a strong dip in the anisotropy profile at
$R_\mathrm{GC}\sim17$ kpc. By directly integrating orbits of particles in a 3-D
model of the Galactic potential with these characteristics, we show that the
$\sigma$ and $\beta$ profiles quickly evolve on a time scale of a
$\mathrm{few}\times10$ Myr whereas the density $\rho$ profile remains largely
unaffected. We suggest that the feature is therefore transient. The origin of
such features in the Galactic halo remains unclear.
