Brief But Spectacular: New Windows into the Physics of Common Envelope Evolution

各种奇异的致密天体只能由两颗恒星的合并形成，这两颗恒星最初在一个紧密的双星轨道上运行。在一个非常短暂的“共同包层阶段”（CE）中，质量最大的恒星膨胀并吞没它的伴星，导致摩擦减少了恒星之间的距离。对后ce系统的观测很少，因此该团队将进行大规模的系统搜索，以发现后ce系统。有了这些结果，该领域的研究人员将能够将他们的计算机模拟与经历了CE阶段的系统的实际轨道和物理特性相匹配。PI诺德豪斯精通美国手语，罗彻斯特理工学院国家聋人技术研究所的学生将被招募到该团队进行暑期研究。利用新近可用的宽视场和时域调查，如盖亚、苔丝和ZTF，该团队将使用一种新的方法来观测确定共同包络演化的初始和最终条件之间的映射。在以下条件下，星团的成员资格对ce前主星的质量产生严格的约束：(i)星团的年龄已知，（ii）白矮星是已确认的星团成员，（iii）白矮星冷却年龄已确定且短于星团年龄，以及（iv）星团的关闭质量大于1.5个太阳质量。在这些条件下，该系统最有可能作为渐近巨支（AGB）恒星进入普通包络阶段。簇还有一个额外的好处，即金属丰度和关闭质量是已知的，从而进一步减少了建模的不确定性。确定和描述一组位于星团中的独立后ce双星的基准，可能对理论的发展和对外来天体的产生率建立可靠的预测具有变革意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A variety of exotic compact objects can be formed only by the merger of two stars that start out in a close binary orbit. During a very short lived “common envelope phase” (CE), the star with the most mass swells and engulfs its companion, resulting in friction that reduces the distance between the stars. Very few observations of post-CE systems exist, so this team will conduct a large-scale systematic search to discover post-CE systems. With these results, researchers in this field will be able to match their computer simulations to the actual orbital and physical properties of systems that have undergone this CE phase. PI Nordhaus is fluent in American Sign Language and students from the Rochester Institute of Technology's National Technical Institute for the Deaf will be recruited for a summer research experience with the team.Leveraging newly available wide-field and time-domain surveys such as Gaia, TESS, and ZTF, the team will use a novel method to observationally determine the mapping between the initial and final conditions of common envelope evolution. Membership in a cluster yields a tight constraint on the pre-CE primary star’s mass under the following conditions: (i.) the cluster’s age is known, (ii.) the white dwarf is a confirmed cluster member, (iii.) the white dwarf cooling age is well determined and shorter than the cluster age, and (iv.) the cluster turn-off mass is above 1.5 solar masses. Under these conditions, the system is most likely to have entered the common envelope phase as an Asymptotic Giant Branch (AGB) star. Clusters have the additional benefit that the metallicity and turn-off masses are known thereby further reducing modeling uncertainty. Identifying and characterizing a set of benchmarks for detached post-CE binaries located in stellar clusters could be transformative to the development of theory and to establishing reliable predictions for production rates of exotic objects.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.