The Evolution of Massive Stars as a Function of Metallicity: Closing the Loop in the Local Group

大质量恒星的演化作为金属丰度的函数：本地群中的闭环

• 批准号: 1008020
• 负责人: Philip Massey
• 金额: $ 80.76万
• 依托单位: Lowell Observatory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1008020&HistoricalAwards=false
• 关键词: Evolution; Massive; Stars; Function; Metallicity

This project will characterize the massive star population of the nearby, star-forming galaxies of the Local Group in order to provide critical tests of stellar evolutionary theory. Current models, while successful in some areas, severely overestimate the lifetimes of the most massive yellow supergiants at high metal abundance ("metal" refers to elements above helium in the periodic table). This project will examine massive stars in several Local Group galaxies, where metallicities differ by a factor of 20. A key goal is to measure mass-loss rates to see how the rates depend upon metallicity. Mass loss largely controls the evolution of massive stars, determining whether a star of 40 solar masses (for example) evolves to a yellow supergiant, red supergiant, and/or a Wolf-Rayet star. The data obtained here will permit critical tests and improvement of the latest evolutionary models. Undergraduate students from Northern Arizona University and Wellesley College will have the opportunity to undertake research as part of this project. Finally, spectra obtained in the present proposal will be made available to other researchers, to enable studies of (for example) the interstellar gas in these galaxies.

该项目将描述附近恒星形成星系群的大量恒星群的特征，以便为恒星演化理论提供关键的测试。当前的模型虽然在某些领域取得了成功，但严重高估了高金属丰度（“金属”是指元素周期表中氦以上的元素）下最大质量的黄色超巨星的寿命。该项目将检查几个本星系群中的大质量恒星，这些星系的金属丰度相差 20 倍。一个关键目标是测量质量损失率，以了解该速率如何取决于金属丰度。 质量损失在很大程度上控制着大质量恒星的演化，决定了一颗 40 个太阳质量的恒星（例如）是否演化为黄超巨星、红超巨星和/或沃尔夫-拉叶星。 这里获得的数据将允许对最新的进化模型进行关键测试和改进。作为该项目的一部分，北亚利桑那大学和韦尔斯利学院的本科生将有机会进行研究。最后，本提案中获得的光谱将提供给其他研究人员，以便能够研究（例如）这些星系中的星际气体。