标题： 银河系 bulge 的场星与星团：星系形成的意义 显示英文标题

标题： Field Stars and Clusters of the Galactic Bulge: Implications for Galaxy Formation

摘要： 基于银河系中心投影距离为1.4-1.8千秒差距的红巨星光谱的银河系核球运动学研究结果被展示。 动力学研究表明，金属丰度与动力学之间存在显著趋势，即贫金属星族的速度弥散较高，而旋转速度较低，与富金属星族相比尤为明显。 [Fe/H] < -1 的K型巨星具有类似晕星族的动力学特性，没有明显的旋转且速度弥散 σ = 120 km/s，与银心距离无关。 对于[Fe/H] > -1 的巨星，其速度弥散随着银心距离的增加而减小，这一星族以 V = 0.9 km/s/度的速度旋转。 目前的观测结果，结合观测到的金属丰度梯度，表明核球形成是通过耗散性坍缩实现的。 在这种模型中，低角动量气体从晕星族的形成过程中丢失，并沉积在核球中。 因此，核球应该比晕星族年轻。 如果我们将距银河系中心3千秒差距内的富金属球状星团归因于核球而非厚盘或晕星族，则银河系球状星团系统的观测结果与此模型一致。 Baade窗口中的RR Lyrae变星的数据也与此模型一致，如果这些恒星被视为内晕的一部分而非核球。 显示英文摘要

摘要： The results of a kinematic study of the Galactic bulge based on spectra of red giants in fields at projected distances of 1.4-1.8 kpc from the Galactic center are presented. There is a marked trend of kinematics with metallicity, in the sense that the more metal-poor population has higher velocity dispersion and lower rotation velocity than the metal-rich population. The K giants more metal--poor than [Fe/H] = -1 have halo-like kinematics, with no significant rotation and sigma = 120 km/s independent of Galactocentric distance. The velocity dispersion of the giants with [Fe/H] > -1 decreases with increasing Galactocentric distance, and this population is rotating with V = 0.9 km/s/degree. The present observations, together with the observed metallicity gradient imply bulge formation through dissipational collapse. In such a picture, low angular momentum gas lost from the formation of the halo was deposited in the bulge. The bulge would then be younger than the halo. Observations of the Galactic globular cluster system are consistent with this picture, if we associate the metal-rich globular clusters within 3 kpc of the Galactic center with the bulge rather than with the thick disk or halo. Data on the RR Lyr in Baade's window are also consistent with this picture if these stars are considered part of the inner halo rather than the bulge.