FABRY-PEROT ABSORPTION LINE SPECTROSCOPY OF THE GALACTIC BAR. I. KINEMATICS

We use Fabry-Perot absorption line imaging spectroscopy to measure radial velocities using the Ca II line in 3360 stars toward three lines of sight in the Milky Way's bar: Baade's Window and offset position at (l, b) similar or equal to (+/- 5.0,-3.5)degrees. This sample includes 2488 bar red clump giants, 339 bar M/K-giants, and 318 disk main-sequence stars. We measure the first four moments of the stellar velocity distribution of the red clump giants, and find it to be symmetric and flat-topped. We also measure the line-of-sight average velocity and dispersion of the red clump giants as a function of distance in the bar. We detect stellar streams at the near and far side of the bar with velocity difference greater than or similar to 30 km s(-1) at l = +/- 5 degrees, but we do not detect two separate streams in Baade's Window. Our M-giants kinematics agree well with previous studies, but have dispersions systematically lower than those of the red clump giants by similar to 10 km s(-1). For the disk main-sequence stars we measure a velocity dispersion of similar to 45 km s(-1) for all three lines-of-sight, placing a majority of them in the thin disk within 3.5 kpc of the Sun, associated with the Sagittarius spiral arm. We measure the equivalent widths of the Ca II lambda 8542 line that can be used to infer metallicities. We find indications of a metallicity gradient with Galactic longitude, with greater metallicity in Baade's Window. We find the bulge to be metal-rich, consistent with some previous studies.