RUI: Using a Large Sample of White Dwarf Stars to Study Stellar Evolution

白色矮星是绝大多数恒星演化的终点。因此，它们是研究恒星生命周期结束阶段的有用的法医探针。一颗白色矮星是一颗紧凑的星星，其质量与太阳相当，体积与地球相当（大约小一百万倍）。 白色矮星不再像太阳那样经历核聚变，而是继续从余热中发光数十亿年。 德克萨斯A M大学商业分校的一个研究小组将开展一项计划，利用盖亚空间使命的数据，结合地面望远镜的观测，将年轻的疏散星团中已知的WD样本增加一倍，或者将数千颗年龄相同的恒星分组。 这些科学家将使用这个大样本的WD来解决一系列天体物理学领域的几个悬而未决的问题，包括：在恒星演化的后期阶段，恒星失去的总质量的变化，超新星或恒星爆炸的祖先的质量较低，紧密的多个星星系统的演化，以及行星系统的命运。 该项目将扩大现有的成功努力，以提高本科生的学习和保留在介绍STEM类提供资金，以培训和指导本科生学习助理修订，以学习者为中心的天文学入门课程。 该项目还将为来自贫困农村地区的第一代大学生和代表性不足的学生提供参与天文学研究的机会。疏散星星团中的白色矮星是研究恒星生命周期末期的多功能和强有力的法医探测器。 特别是，白色矮星的研究使我们能够限制总质量损失的恒星在其主序后的演变，较低的质量限制核心坍缩超新星的祖先，双简并系统的形成率，红巨星核心的旋转速率和他们的耦合到星星的信封，和白色矮星大气和结构的演变。 星星中的白色矮星是特别有用的工具，这在很大程度上是因为许多关键的恒星参数是已知的，包括总年龄（白色矮星冷却时间加上祖先寿命）和金属丰度。 该项目建立在研究人员对疏散星团中的白色矮星的早期研究的基础上;盖亚使命的视差和自行数据以及疏散星团的多历元深度成像实际上消除了星团成员的不确定性，大大减少了目前已发表文献中做出的推断数量。 通过使用国家、州和地方大学的设施，研究人员希望将已知的疏散星团白色矮星的数量增加近一倍，并能够实施白色矮星形成和演化的集合研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

White dwarf (WD) stars are the endpoint of stellar evolution for the vast majority of stars. As such, they are useful forensic probes for studying the end stages of the stellar life cycle. A white dwarf is a compact star that contains the mass of the Sun within a volume comparable to that of the Earth (about a million times smaller). White dwarfs no longer undergo nuclear fusion like the Sun, but continue to glow from residual heat for billions of years. A research group at Texas A&M University-Commerce will carry out a program to use data from the Gaia space mission combined with observations from ground-based telescopes to double the sample of known WDs in young open clusters, or groupings of a few thousand stars of about the same age. These scientists will use this large sample of WDs to address several open questions in a range of astrophysical areas including: variability in total mass lost by stars during late stages of stellar evolution, the lower mass of the progenitors of supernovae, or stellar explosions, the evolution of close multiple star systems, and the fate of planetary systems. This project will expand an existing successful effort to improve undergraduate student learning and retention in introductory STEM classes by providing funding to train and mentor undergraduate learning assistants for revised, learner-centered introductory astronomy courses. The project will also offer first-generation college students and underrepresented students from depressed rural areas opportunities to participate in astronomy research.White dwarf stars in open star clusters are versatile and powerful forensic probes for studying the end stages of the stellar life cycle. In particular, white dwarf studies allow us to constrain the total mass lost by stars during their post-main sequence evolution, the lower mass limit for core-collapse supernova progenitors, the formation rate of double degenerate systems, rotation rates of red giant cores and their coupling to the star's envelope, and white dwarf atmospheric and structural evolution. White dwarfs in open star clusters are especially useful tools in large part because the many crucial stellar parameters are known, including total age (white dwarf cooling time plus progenitor lifetime) and metallicity. The project builds on earlier studies of white dwarf stars in open clusters made by the investigators; parallax and proper motion data from the Gaia mission and multi-epoch deep imaging of open clusters virtually eliminates uncertainties in cluster membership, vastly reducing the number of inferences currently made in the published literature. Through the use of national, state and local university facilities, the researchers expect to nearly double the number known open cluster white dwarfs and to be able to implement ensemble studies of white dwarf formation and evolution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.