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 \pm 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 .