White Dwarfs in Open Clusters

该项目的研究人员正在对年轻疏散星团中的白矮星进行广泛的搜索，主要目标是确定主序恒星质量，在该质量以上，恒星以核心塌缩超新星的形式爆炸，在低于该质量的情况下，恒星以白矮星的形式结束生命。这一临界质量的值在许多领域都很重要。恒星群中核心塌缩超新星的数量对星系中的化学浓缩和能量平衡具有重要意义。超新星动能反馈可能是矮小星系早期演化的主导过程，也是调节所有质量年轻星系恒星形成的重要机制。目前临界质量值的不确定性很大，最近的文献中的值在5到8个太阳质量之间。确定白矮星形成的临界质量对于限制巨型恒星的物理过程也很重要，这些物理过程导致核心的形成和增长，最终成为白矮星的残留物。这一计划的一个有价值的附带好处是改进了对一些年轻和中年疏散星系团的年龄、距离和初始质量函数的估计。更广泛的影响。在研究过程中，研究人员在WWW网站上免费提供他们的数据和分析工具。天文学和物理学的研究生和本科生都参与了这项研究。

AST 0307492Bolte, Michael J.The investigators in this project are carrying out an extensive search for white dwarf stars in young open clusters with the primary goal to identify the main sequence stellar mass above which stars explode as core collapse supernovae and below which stars end their lives as white dwarfs. The value for this critical mass is important in a wide range of areas. The number of core-collapse supernovae in a stellar population has important implications for chemical enrichment and energy balance in galaxies. Supernovae kinetic energy feedback may be the dominant process in the early evolution of dwarf galaxies and is an important mechanism for regulating star formation in young galaxies of all masses. The current uncertainty in the value of the critical mass is large with values in the recent literature ranging from 5 to 8 solar masses. Identifying the critical mass for the formation of white dwarfs is also important for providing constraints on physical processes in giant stars that lead to the formation and growth of the core that eventually becomes thewhite dwarf remnant. A valuable side benefit of this program is improved estimates of the ages, distances and initial mass functions of a number of young and intermediate-age open clusters. Broader Impact. The researchers are making their data and analysis tools available freely at a WWW site during the course of the work. Astronomy and physics graduate and undergraduate students are involved in the research.