Collaborative Research: Age-Dating M31's Halo and Satellites - Testing the Lambda CDM Paradigm

恒星晕是围绕螺旋星系旋转的大致球形的恒星云，它提供了对星系形成和演化的独特洞察，它们可能是理解暗物质的关键。从我们在银河系内部的位置来看，我们无法完全探测我们自己的光环，因为它的大部分都被我们的视线挡住了。M31(“仙女座星系”)距离我们足够近，我们可以在它的光晕中测量单个恒星的性质。该计划将利用现有数据并获得M31的新观测数据，以绘制其整个光晕的恒星年龄分布图。这将使他们能够确定几种不同机制的相对重要性，这些机制可以将恒星添加到星系晕中。最终，这将使我们更好地了解我们银河系的历史。该项目将为两所院校的本科生和研究生研究创造机会。弗吉尼亚大学的小组与业余天文学家合作开展星系进化研究项目，并向弗吉尼亚州农村地区的K-12学生推广项目。加州大学圣克鲁斯分校的团队通过宇宙、魔法和科学实习计划教授未被充分代表的高中生。这两个专业人士都教授大型本科课程，积极指导学生，定期进行公开演讲，并在K-12课堂上演讲。这些个人专业人士将创建M31星晕的第一个年龄分布概况。这项工作利用了过去10年(SPLASH项目)对望远镜时间的巨大投资，目的是增加两个重要的新参数：金属丰度和年龄分布。将应用三种新的观测方法，包括跨越M31晕的近红外成像测量，距离为180kpc，M31卫星星系中异常造父变星的光学时间序列，以及M31场和dSph恒星的Keck/Deimos光谱。这项工作利用了过去10年(SPLASH项目)对望远镜时间的巨大投资，目的是增加两个重要的新参数：金属丰度和年龄分布。

Stellar halos, the roughly spherical clould of stars orbiting a spiral galaxy, provide unique insight into the formation and evolution of galaxies, and they may hold the key to understanding dark matter. From our position inside the Milky Way, we are unable to fully probe our own halo, because much of it is blocked from our view. M31 (the "Andromeda Galaxy") is near enough that we can measure properties of individual stars in its halo. This program will utilize existing data and obtain new observations of M31 in order to map the distribution star ages throughout its halo. This will permit them to determine the relative importance of several different mechanisms that can add stars to a galaxy halo. Ultimately, this will lead to a better understanding of the history of our own Milky Way galaxy. This program will create opportunities for both undergraduate and graduate student research at two institutions. The University of Virginia group works with amateur astronomers on galaxy evolution research projects and outreach programs to K-12 students in rural Virginia. The University of California - Santa Cruz team teaches underrepresented high school students through the COSMOS, MAGIC, and the Science Internship Programs. Both of the PIs teach large undergraduate courses, actively mentor students, give regular public lectures and speak in K-12 classrooms.The PIs will create the first age-distribution profile of the M31 stellar halo. This work leverages an enormous investment of telescope time over the past 10 years (the SPLASH project) and aims to add two significant new parameters: metallicity and age distributions. Three new observational methods will be applied, including a near infrared imaging survey across the M31 halo out to a distance of 180 kpc, optical time series of anomalous Cepheids in M31 satellite galaxies, and Keck/DEIMOS spectroscopy of M31 field and dSph stars. This work leverages an enormous investment of telescope time over the past 10 years (the SPLASH project) and aims to add two significant new parameters: metallicity and age distributions.