Kinematics and Abundances of the Galactic and M31 Bulges

Dr. R.加州-洛杉矶大学的迈克尔·里奇将利用从2微米全天成像巡天（2 MASS）中选出的M巨星，并利用塞罗托洛洛美洲天文台的水螅多光纤光谱仪进行观测，对银河系核球的径向速度进行大规模研究。 研究人员已经证明，M巨星是非常好的运动学探测器，可以在整个银河系的凸起进行研究，即使在高消光区也是如此;最终的10，000个径向速度的样本比以前的研究大10倍。里奇博士开发了径向速度测量精度为3公里/秒的技术，从而有可能发现隆起中的冷运动学特征（如果存在）。 比较由此产生的椭圆速度图，短轴旋转曲线，和其他速度数据与自洽模型的银河系隆起/酒吧，将允许洞察银河系隆起的形成。 此外，里奇博士还将利用红外光谱法获得银河系和M31凸出部分恒星的详细丰度。 对于银河系的膨胀，他将使用凯克天文台的NIRSPEC阶梯光谱仪观察至少150颗距离核30到300 pc的恒星。 该计划将把详细的丰度测量扩展到星系核附近被尘埃遮挡的区域。丰度梯度的存在与否限制了棒长期演化的模型，而成分（例如氧丰度）的测量可以限制原始恒星群的形成时间尺度和初始质量函数。Rich博士将通过支持博士学位，为下一代天文学家的培训做出贡献。学生的论文正在进行中，也研究由本科生和博士后科学家通过这个程序。 银河系膨胀径向速度调查和由此产生的模型将提供给海登天文馆，海登天文馆正在建造一个虚拟的银河系，公众可以在模拟飞行中观察到，他将探索数据的其他可视化，将结果带给公众。 将向天文学界提供包含约10，000颗恒星的光谱学和径向速度的整个数据库。

Dr. R. Michael Rich, of the University of California - Los Angeles, will undertake a large scale radial velocity study of the Galactic bulge using M giants selected from the Two Micron All-sky Imaging Survey (2MASS) and observed using the Hydra multifiber spectrograph at Cerro Tololo Inter-American Observatory. The investigator has shown that the M giants make excellent kinematic probes that can be studied over the entirety of the Galactic bulge, even in high extinction regions; the ultimate sample of 10,000 radial velocities is a factor of ten greater than previous studies. Dr. Rich has developed techniques that give a precision of 3 km/s for radial velocity measurements, making it possible to discover cold kinematic features in the bulge, if present. Comparison of the resulting longitude-velocity diagrams, minor axis rotation curves, and other velocity data with self-consistent models of the Galactic bulge/bar, will allow for insight into the formation of the Galactic bulge. In addition, Dr. Rich will obtain detailed abundances for stars in the bulges of the Milky Way and M31 using infrared spectroscopy. For the Milky Way bulge, he will observe at least 150 stars ranging from 30 to 300 pc from the nucleus using the NIRSPEC echelle spectrograph at the Keck observatory. This program will extend detailed abundance measurements into regions of the Galaxy that are near the nucleus and are obscured by dust. The presence or absence of an abundance gradient constrains models of secular evolution of the bar, while measurements of composition (e.g. oxygen abundance) can constrain the formation timescale and the initial mass function of the primordial stellar population.Dr. Rich will contribute to the training of the next generation of astronomers by supporting a Ph.D. student whose thesis is in progress and also research by an undergraduate student and a postdoctoral scientist through this program. The Galactic bulge radial velocity survey and the resulting models will be made available to the Hayden Planetarium, which is building a virtual Milky Way Galaxy that can be observed by the public in a simulated fly-through, and he will explore other visualizations of the data to bring the results to the public. The entire database of ~10,000 stars with spectroscopy and radial velocities will be made available to the astronomical community.