The Pattern Speed of the Galactic Bar
Abstract
Most late-type stars in the solar neighborhood have velocities similar to the local standard of rest (LSR), but there is a clearly separated secondary component corresponding to a slower rotation and a mean outward motion. Detailed simulations of the response of a stellar disk to a central bar show that such a bi-modality is expected from outer-Lindblad resonant scattering. When constraining the run of the rotation curve by the proper motion of Sgr A* and the terminal gas velocities, the value observed for the rotation velocity separating the two components results in a value of (53+/-3)km/s/kpc for the pattern speed of the bar, only weakly dependent on the precise values for Ro and bar angle phi.
Cite
@article{arxiv.astro-ph/9908105,
title = {The Pattern Speed of the Galactic Bar},
author = {Walter Dehnen},
journal= {arXiv preprint arXiv:astro-ph/9908105},
year = {2009}
}
Comments
5 pages LaTeX, 2 Figs, accepted for publication in ApJ Letters