RUI: Stellar Populations in Nearby Dwarf Galaxies

这个项目的目标是了解银河系的聚集，它的光晕的聚集，以及矮星系中暗物质晕的行为。这次观测的目标是斯隆数字巡天（SDSS）发现的本星系群中的矮星系。这些微弱的、低密度的球状系统经历了潮汐相互作用，它们的恒星群被搅动起来。另一个目标是明显不太受干扰的不规则的Wolf-Lundmark-Melotte （WLM）星系，它离银河系的暗物质晕更远。这些观测可能有助于区分在暗物质晕中形成的原始物体和在星系间潮汐相互作用中形成的物体。在这些新发现的矮星系统中，已经有大量的恒星被阿帕奇角天文台（APO） 3.5米和CTIO 4米望远镜观测到。在这里，完成了对恒星群的华盛顿和斯特伦格伦光度测定，并对其进行了分析，以获得恒星的金属丰度和年龄。额外的低分辨率光谱被用来进一步探测金属丰度，并检查被观测恒星的成员。反过来，这些信息限制了这些暗矮星系统的初始质量函数和恒星形成历史。该项目支持一所本科院校的研究，并将介绍几名本科生进行科学研究。

The goals of this project are to understand the assembly of the Milky Way, the assembly of its halo, and the behavior of dark matter halos in dwarf galaxies. The observations target dwarf galaxies in the Local Group which have been discovered by the Sloan Digital Sky Survey (SDSS). These faint, low-density, spheroidal, systems have experience tidal interactions and their stellar populations are stirred up. Another target is the apparently less disturbed, irregular Wolf-Lundmark-Melotte (WLM) galaxy that is more remote from the Milky Way's dark matter halo. The observations may help to distinguish between primordial objects made in dark matter halos, and objects formed in tidal interactions between galaxies. A large number of stars in the fields of these newly discovered dwarfs ystems has already been observed with the Apache Point Observatory (APO) 3.5m and the CTIO 4-m telescopes. Here the Washington and Stromgren photometry of stellar populations is completed and analyzed to obtain stellar metallicities and ages. Additional low-resolution spectroscopy is used to further probe metallicities, and check on the memberships of the observed stars. In turn, this information constrains the initial mass functions and star formation histories of these faint dwarf systems. This project supports research at an undergraduate institution and will introduce several undergraduate students to scientific research.