Probing the Galaxy's bars via the Hercules stream
  It has been suggested that a resonance between a rotating bar and stars in
the solar neighbourhood can produce the so called 'Hercules stream'. Recently,
a second bar may have been identified in the Galactic centre, the so called
'long bar', which is longer and much flatter than the traditional Galactic bar,
and has a similar mass. We looked at the dynamical effects of both bars,
separately and together, on orbits of stars integrated backwards from local
position and velocities, and a model of the Galactic potential which includes
the bars directly. Both bars can produce Hercules like features, and allow us
to measure the rotation rate of the bar(s). We measure a pattern speed, for
both bars, of 1.87 +/- 0.02 times the local circular frequency. This is on par
with previous measurements for the Galactic bar, although we do adopt a
slightly different Solar motion. Finally, we identify a new kinematic feature
in local velocity space, caused by the long bar, which is tempting to identify
with the high velocity 'Arcturus' stream.
