利用外晕球状星团研究M31的形成和演化

星系外晕中的球状星团保留着寄主星系动力学和化学演化的信息，对它们的研究有助于解决星系的起源、演化问题。M31是距离我们最近的巨旋涡星系，其晕中大量的子结构表明M31可能在几个Gyr前与一个（或一些）较小的星系发生过并合。然而，对于M31外晕中的球状星团，目前尚缺乏细致、系统的研究，严重限制了我们深入理解M31与周围星系的相互作用历史。我们计划利用最新的观测数据对M31外晕球状星团进行研究：即以BATC 15色测光为主，结合GALEX、SDSS、Pan-STARRS和2MASS等巡天的观测资料，拟合星族合成模型求得M31外晕球状星团的金属丰度、年龄和质量；对这些星团的各项性质进行统计分析，并与M31内晕、盘上以及银河系外晕球状星团的星族成分进行对比研究，剖析M31的吸积历史。申请人对M31盘上的星团进行了一系列工作，对M31的演化有一定研究，与本项目结合，有助于全方位重构M31的演化图像。

Globular clusters (GCs) in the galaxy outer halo contain the information of the dynamical and chemical evolution of the host galaxy, and the study on them will help understand how a galaxy forms and evolves. Recently, many complicated substructures were discovered in the M31 halo, implying that some mergers between M31 and other smaller galaxies may occur a few Gyr ago. However, the GCs in the M31 outer halo are lack of detailed and systematic studies, which restrain us from understanding the interaction history between M31 and surround galaxies. We plan to study GCs in the outer halo of M31 based on the newest observed data from 15 BATC intermediate-band filters, and the archive data from GALEX, SDSS, Pan-STARRS, and 2MASS, with the newest stellar population synthesis models. The metallicities, ages, and masses will be determined for these GCs. Finally, we will compare the stellar populations between them and the counterparts in the inner halo and disk of M31 and in the outer halo of the Milky Way. The applicant has made a series of studies on disk clusters in M31, and with this program, we could comprehensively reconstruct the evolution history of M31.