The Internal Kinematics of Dwarf Spheroidal Galaxies: Do they Contain Dark Matter?

现在已经确定，宇宙的大部分是由不发光的物质组成的，但很少或根本没有证据表明这种物质可能是什么。某些星系（矮球状星系）被认为是包含暗物质的最局部的外部系统，也是最简单的星系类型。它们含有很少或没有气体，恒星形成的历史也相对简单。对这些星系进行细致的运动学研究，可能会为暗物质的本质提供最明确的证据。这项由该基金支持的研究将测量三个矮球状星系中恒星的精确速度，以测量这些星系中恒星的速度色散。在这些系统中获得精确的速度将允许测量这些星系的引力势。我们对这些星系的精确结构所知甚少，光度测定将大大提高我们对这些低光度星系结构的认识。

It is now well established that much of the Universe is composed of nonluminous matter, but there is little or no evidence for what this material might be. Certain galaxies (dwarf spheroidal galaxies) are the most local external systems thought to contain dark matter, and are the simplest type of galaxy. They contain little or no gas and have had relatively simple star formation histories. Careful kinematic studies of these galaxies may provide the least ambiguous evidence for the nature of dark matter. The research to be supported by this grant will measure precise velocities of stars in three dwarf spheroidal galaxies in order to measure the velocity dispersion of the stars in these systems. The acquisition of precise velocities in each of these systems will allow the gravitational potential of these galaxies to be measured. The precise structure of these galaxies is rather poorly known, and photometry will be obtained which will substantially improve our knowledge of the structure of these low luminosity galaxies.