Low-Velocity Streams in the Solar Neighborhood Caused by the Galactic
  Bar
  We find that a steady state bar induces transient features at low velocities
in the solar neighborhood velocity distribution due to the initial response of
the disc, following the formation of the bar. We associate these velocity
streams with two quasi-periodic orbital families, librating around the stable
x_1(1) and x_1(2) orbits near the bar's outer Lindblad resonance (OLR). In a
reference frame moving with the bar, these otherwise stationary orbits precess
on a timescale dependent on the strength of the bar, consistent with
predictions from a simple Hamiltonian model for the resonance. This behavior
allows the two orbital families to reach the solar neighborhood and manifest
themselves as clumps in the u-v plane moving away from (x_1(2)), and toward
(x_1(1)) the Galactic center. Depending on the bar parameters and time since
its formation, this model is consistent with the Pleiades and Coma Berenices,
or Pleiades and Sirius moving groups seen in the Hipparcos stellar velocity
distribution, if the Milky Way bar angle is 30<phi_0<45 [deg] and its pattern
speed is Omega_b/Omega_0=1.82\pm 0.07, where Omega_0 is the angular velocity of
the local standard of rest (LSR). Since the process is recurrent, we can
achieve a good match about every six LSR rotations. However, to be consistent
with the fraction of stars in the Pleiades, we estimate that the Milky Way bar
formed ~2 Gyr ago. This model argues against a common dynamical origin for the
Hyades and Pleiades moving groups.
