Mapping Microlensing and Stellar Variability in M31

绘制 M31 中的微透镜和恒星变率

• 批准号: 0070882
• 负责人: Arlin P. Crotts
• 金额: $ 39.63万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0070882&HistoricalAwards=false
• 关键词: Mapping; Microlensing; Stellar; Variability; M31; Mapping; Microlensing; Stellar; Variability; M31

CrottsAST-0070882The principal investigator and colleagues propose to study micolensing events in M31, using the background stars in that galaxy to identify microlenses in both M31 itself and in our own galaxy. The rate of lensing events is expected to be higher in M31 than in our galaxy or the LMC because the inclination of M31 allows us to see through a greater column density of stars. In addition to lensing objects, the surveys will also find intrinsically variable stars (such as Mira variables). A key question today in astrophysics is what composes the dark matter known to exist in galaxies. A crucial clue comes from observations which indicate that a large fraction of the mass of our Galaxy may be due to "Massive, Compact Halo Objects" (MACHOs), an interpretation which is highly controversial and difficult to understand. This proposal is to fund a three-year observational program, involving our nearest neighboring, large galaxy, M31 in Andromeda, which will settle the question of whether a large part of galaxy dark matter is composed of stellar massed objects in the halo. These results can be obtained well in advance of competing, proposed approaches, and settle the current quandary within the context of a galaxy separate from our own, indicating whether the MACHO halo is a universal phenomenon. The proposed study can address unsettled questions from Galactic surveys about the structure and content of the central Bulge, as well as produce a comprehensive assay of variable stars in M31, whichcan be used for several, new astronomical studies. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).****

Crottsast-0070882首席研究员及其同事建议使用该星系中的背景恒星研究M31中的涂压事件，以识别M31本身和我们自己的星系中的微透镜。预计在M31中，镜头事件的速率将高于我们的星系或LMC，因为M31的倾斜度使我们能够透明恒星的更大柱密度。除了镜头对象外，调查还将找到本质上可变的恒星（例如MIRA变量）。今天，天体物理学的一个关键问题是，什么组成了星系中存在的暗物质。 一个关键的线索来自观察结果，表明我们银河系的质量很大一部分可能是由于“大量，紧凑的光环对象”（Machos）引起的，这是一种高度争议且难以理解的解释。 该提议是为一个为期三年的观察计划提供资金，涉及我们最近的邻居Galaxy，M31在仙女座中，该计划将解决一个问题，即大部分星系暗物质是否由光环中的恒星质量物体组成。 这些结果可以在竞争，提出的方法之前很好地获得，并在我们与我们自己的星系中分开的背景下解决当前的难题，这表明男子气概的光环是否是普遍现象。拟议的研究可以解决有关中央凸起的结构和内容的银河调查中未解决的问题，并在M31中对可变恒星进行了全面的测定，可用于几项新的天文学研究。该项目的资金由NSF外部天文学和宇宙学计划（AST/EXC）提供。****