Collaborative Research: Structure and Evolution of M31's Stellar Halo from a Large-Scale Spectroscopic Survey

建议编号：AST-0307966PI：Puragra GuhathakurtaINSTUTION：加州大学圣塔库尔塔分校的Puragra Guhathakurta(AST-0307966)领导的合作项目，包括加州大学洛杉矶分校的Michael Rich(AST-0307931)，弗吉尼亚大学的Steven Majewski(AST-0307842)和卫斯理大学的Kathryn Johnston(AST-0307846)。这个合作者团队将通过进行大规模的光谱测量来提高我们对M31光晕的性质和起源的理解，这将产生恒星径向速度和金属元素。更大的样本将允许他们通过确定平均金属丰度分布函数、外旋转曲线和光晕的速度弥散来探索光环/外盘恒星群在很大范围内的银心距离。他们的研究将集中在最近从广域成像测量中发现的光晕中离散物质流中恒星的结果。最终，他们的样本应该可以让他们评估M31对卫星星系的破坏在多大程度上促进了晕群的形成。所有的合作者都让本科生和研究生参与他们的研究工作。他们希望在K-12课堂上进行公开演讲和演讲，介绍他们的研究成果，并让公众了解他们的工作成果。他们还计划购买一个窄带滤光片，用于研究钙红外三联体，这将向所有使用凯克望远镜的用户提供。

PROPOSAL NO: AST-0307966PI: Puragra GuhathakurtaINSTITUTION: University of California, Santa Cruz================================================================This collaborative project is led by Puragra Guhathakurta of UCSC (AST-0307966), and includes Michael Rich of UCLA (AST-0307931), Steven Majewski of University of Virginia (AST-0307842) and Kathryn Johnston of Wesleyan University (AST-0307846).This team of collaborators will improve our understanding of the nature and origin of the halo of M31 by carrying out a large-scale spectroscopic survey that will yield both stellar radial velocities and metallicities. The larger sample will allow them to explore the halo/outer disk stellar population over a wide range of galactocentric distances by determining the mean metallicity distribution function, the outer rotation curve, and the velocity dispersion of the halo. Their study will focus on results for stars in the discrete streams of material in the halo that have been discovered recently from wide field imaging surveys. Ultimately, their sample should allow them to assess the extent to which the disruption of satellite galaxies accreted by M31 has contributed to the formation of the halo population. All of the collaborators involve undergraduate and graduate students in their research efforts. They expect to give public lectures and to speak in K-12 classrooms about their research and to make the results of their work accessible to the public. They also plan to purchase a narrow band filter for work on the Ca infrared triplet, which will be made available to all users of the Keck telescopes.