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

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提议研究M31中的微透镜事件，利用该星系中的背景恒星来识别M31本身和我们银河系中的微透镜。M31中的透镜事件率预计会比我们的银河系或大麦哲伦星系更高，因为M31的倾角允许我们透过更大的恒星柱密度看到。除了透镜天体，巡天还将发现本质变星（如Mira变星）。今天天体物理学的一个关键问题是，已知存在于星系中的暗物质是由什么组成的。 一个关键的线索来自于观测，它表明我们银河系的大部分质量可能是由于“大质量致密晕天体”（MACHO），这是一个非常有争议和难以理解的解释。 这项提议将资助一项为期三年的观测计划，涉及我们最近的邻居，仙女座的大星系M31，这将解决星系暗物质的大部分是否由晕中的恒星质量物体组成的问题。 这些结果可以在竞争之前获得，提出的方法，并解决当前的困境，在一个星系的背景下，从我们自己的，表明是否是一个普遍的现象，NH 4 O晕。这项拟议中的研究可以解决银河系巡天中关于中央隆起结构和内容的未解决问题，并对M31中的变星进行全面分析，这可用于几项新的天文学研究。该项目的资金由美国国家科学基金会的河外天文宇宙学计划（AST/EXC）提供。