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恒星形成的大致球形云，为星系的形成和演化提供了独特的视角，它们可能是理解暗物质的关键。从我们在银河系内的位置来看，我们无法完全探测到我们自己的光环，因为它的大部分都被挡住了我们的视线。M31（“仙女座星系”）离我们足够近，我们可以测量其光晕中单个恒星的特性。该计划将利用现有数据并获得M31的新观测结果，以便绘制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，这将有助于我们更好地了解银河系的历史。该项目将为两个机构的本科生和研究生的研究创造机会。弗吉尼亚大学的小组与业余天文学家一起进行星系演化研究项目，并向弗吉尼亚农村地区的K-12学生提供推广计划。加州大学圣克鲁斯分校的团队通过COSMOS、MAGIC和科学实习项目来教授代表性不足的高中生。这两位pi教授大量的本科课程，积极指导学生，定期进行公开讲座，并在K-12教室演讲。PIs将创建M31恒星光晕的第一个年龄分布剖面。这项工作利用了过去10年望远镜时间的巨大投资（SPLASH项目），旨在增加两个重要的新参数：金属丰度和年龄分布。将采用三种新的观测方法，包括横跨M31光晕的近红外成像巡天，距离为180 kpc， 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年望远镜时间的巨大投资（SPLASH项目），旨在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.