Collaborative Project: The Internal Kinematics of Dwarf Spheroidal Galaxies: Do They Contain Dark Matter? (Part I of 2 Projects)

一系列广泛的成像和光谱 旨在测试和测量的观察和分析 矮星系中暗物质的分布 在这项研究中将进行一个球状星系 格兰特. 的速度分散，或特征宽度， 狮子座I和狮子座II系统中的恒星将被测量， 第一次 这些都是决定 在另一颗矮行星上测得的大速度色散 球状星系是由潮汐或 暗物质 多光纤光谱数据已经被 为小熊座、天龙座和六星座的侏儒收集的 星系 结合天炉座星系的阶梯光栅数据 通过新的观测，这些数据将使 这些星系的引力势，而不仅仅是它们的引力势 质量，有待确定。 质光比的测量 遥远的晕球状星团NGC 2419的比率， 被认为不含暗物质，将提供必要的 比较时，评估的质光比的 矮球状星系 广泛的成像数据， 改善或测量这些低光度的结构 星系被收集起来。 最后，无线电 一些有趣的无线电源的观测， 将制作光学对应物。 该项目是与Mario Mateo博士的合作项目 密歇根大学安阿伯分校（AST 9223968）。

An extensive series of imaging and spectroscopic observations and analysis designed to test for and measure the distribution of the putative dark matter in dwarf spheroidal galaxies will be carried out in this research grant. The velocity dispersion, or characteristic width, of stars in the Leo I and Leo II systems will be measured for the first time. These are key objects for deciding if the large velocity dispersions measured in the other dwarf spheroidal galaxies are caused by tides or the presence of dark matter. Multifiber spectroscopic data have been collected for the Ursa Minor, Draco, and Sextan dwarf galaxies. Combined with echelle data for the Fornax galaxy and with new observations, these data will allow the gravitational potential of these galaxies, not just their mass, to be determined. Measurement of the mass-to-light ratio of the distant halo globular cluster NGC2419, which is thought to contain no dark matter, will provide a necessary comparison when assessing the mass-to-light ratios of the dwarf spheroidal galaxies. Extensive imaging data to improve or measure the structure of these low luminosity galaxies has been collected. Finally, further radio observations of some intriguing radio sources with no optical counterparts will be made. This project is a collaborative project with Dr. Mario Mateo of the University of Michigan at Ann Arbor (AST 9223968).