Low-velocity streams in the solar neighbourhood caused by the Galactic bar

摘要: We find that a steady state bar induces transient features at low velocities in the solar neighborhood velocity distribution due to initial response of disc, following formation bar. associate these streams with two quasi-periodic orbital families, librating around stable x1(1) and x1(2) orbits near bar’s outer Lindblad resonance (OLR). In reference frame moving bar, otherwise stationary precess on timescale dependent strength consistent predictions from simple Hamiltonian model for resonance. This behavior allows families reach manifest themselves as clumps u-v plane away (x1(2)), toward (x1(1)) Galactic center. Depending parameters time since its formation, this is Pleiades Coma Berenices, or Sirius groups seen Hipparcos stellar distribution, if Milky Way angle 30 � . �0 45 pattern speed b=0 = 1:82±0:07, where 0 angular local standard rest (LSR). Since process recurrent, we can achieve good match about every six LSR rotations. However, be fraction stars Pleiades, estimate formed 2 Gyr ago. argues against common dynamical origin Hyades groups. Subject headings: dynamics,