银河棒的法布里-珀罗吸收谱。I.运动学
Fabry-Perot Absorption Line Spectroscopy of the Galactic Bar. I. Kinematics
摘要：
我们用Fabry-Perot吸收线成像光谱法测量了3360颗恒星的Ca Ⅱ 8542谱线在Baade窗和（l，b）~（+-5.0，-3.5）处的视向速度。这个样本包括2488颗棒状红丛巨星、339颗棒状M/K巨星和318颗盘状主序星。我们测量了红团簇巨星的恒星速度分布的前四阶矩，发现它是对称的平顶分布。我们还测量了红团簇巨星的视线平均速度和色散随棒中距离的变化。我们在棒的近端和远端探测到速度差大于30 km/s的恒星流，在l = +-5处，但我们没有在巴德窗探测到两个独立的恒星流。我们的M-巨星运动学与以前的研究一致，但色散系统地低于红团巨星的色散约10 km/s。对于盘主序星，我们测量的速度色散~ 45公里/秒的所有三条视线，其中大部分放置在薄盘3.5千秒差距内的太阳，与人马座spiral arm. We测量的Ca II 8542线，可用于推断金属丰度的等效宽度。我们发现金属丰度梯度与银河经度的迹象，与更大的金属丰度在巴德窗口。我们发现凸起富含金属，与以前的一些研究一致。
英文摘要：
We use Fabry-Perot absorption line imaging spectroscopy to measure radial velocities using the Ca II 8542 line in 3360 stars towards three lines of sight in the Milky Way's bar: Baade's Window and offset position at (l,b) ~ (+-5.0, -3.5). 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 > 30 km/s at l = +-5, 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 ~ 10 km/s. For the disk main sequence stars we measure a velocity dispersion of ~ 45 km/s 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 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.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
