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以近距离双星轨道开始的恒星合并形成。在一个非常短暂的“共同包络相”（CE）中，质量最大的星星膨胀并吞没了它的伴星，导致恒星之间的摩擦减少了恒星之间的距离。对后CE系统的观察很少，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 Nordhaus精通美国手语，来自罗切斯特理工学院国家聋人技术研究所的学生将被招募参加该团队的夏季研究体验。该团队将利用最新的宽场和时域调查，如Gaia，TESS和ZTF，使用一种新的方法来观察确定共同包络演变的初始和最终条件之间的映射。在以下条件下，星团成员对CE前主星星的质量产生严格的约束：（i.）已知簇的年龄，（ii.）该白色矮星是一个确认的集群成员，（iii.）白色矮星的冷却年龄是很好的确定和短于集群年龄，和（iv.）星团的关闭质量超过1.5个太阳质量。在这些条件下，系统最有可能以渐近巨分支（AGB）星星的形式进入共包络相。团簇具有额外的好处，即金属丰度和关闭质量是已知的，从而进一步降低建模的不确定性。识别和表征一组基准分离后CE双星位于星团可能是变革的理论发展，并建立可靠的预测生产率的异国情调objects.This奖项反映了NSF的法定使命，并已被认为是值得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的支持。

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.