All-sky Precise Stellar Ages for Galactic and Stellar Archaeology

星星的年龄很难辨别。 恒星的年龄是非常重要的，因为恒星的组成随时间而变化。 许多与我们银河系起源有关的问题将通过更好的恒星年龄和成分来回答。研究小组已经开发出一种程序来辨别一种称为“次巨星”的恒星的年龄。 研究小组将计算数十万颗次巨星的精确年龄和成分。 然后，他们将利用这些结果来研究我们银河系的形成和演化。 来自约翰霍普金斯大学和全国黑人物理学家协会的学生将参与这项工作。 研究小组还将在大都会巴尔的摩的男孩女孩俱乐部举办天文馆展览。恒星的年龄很难精确推断。 即使用开普勒星震学对恒星进行最仔细的分析，也只能提供精确到不超过10%的模型依赖年龄。这些不精确的年龄阻碍了银河系和恒星考古学的发展。 对于贫金属恒星来说，这个问题甚至更加严重，在天空中只有少数恒星具有足够的视星等，原则上可以进行10%的精确年龄推断。研究人员将以1%的精度制作第一个也是最大的恒星年龄全天空目录。该目录还将包括光球恒星参数（即，有效温度、表面重力和金属丰度），基本恒星参数（即，质量和年龄）和银河系轨道。 它将产生均匀推断的年龄-金属丰度-轨道分布的薄盘，厚盘，和银河系的晕。 薄盘、厚盘和晕的相对年龄将揭示它们形成的物理过程。 此外，该奖项还将使银河系中所有金属丰度的最古老恒星的分离成为可能。该奖项反映了NSF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。

The ages of stars are hard to discern. Stellar ages are very important because the compositions of stars change with time. Many questions related to the origin of our own Milky Way Galaxy will be answered with better stellar ages and compositions. The research team has developed a procedure to discern ages for a type of stars called ``subgiants''. The research team will calculate precise ages and compositions for hundreds of thousands of subgiants. They will then use these results to the study the formation and evolution of our own Milky Way Galaxy. Students from Johns Hopkins University and the National Society of Black Physicists will be part of this effort. The research team will also work to put on planetarium shows at Boys & Girls Clubs of Metropolitan Baltimore.Stellar ages are difficult to precisely infer. Even the most careful analyses of stars with Kepler asteroseismology only provide model-dependent ages precise to no better than 10%. These imprecise ages are holding back the fields of Galactic and stellar archaeology. The problem is even more acute for metal-poor stars, of which there are few of sufficient apparent magnitude in the parts of the sky where 10% precision age inferences are in principle possible. The investigator will produce the first and largest all-sky catalog of stellar ages with 1% accuracy. This catalog will also include photospheric stellar parameters (i.e., effective temperature, surface gravity, and metallicity), fundamental stellar parameters (i.e., mass and age), and Galactic orbits. It will yield homogeneously inferred age--metallicity--orbit distributions for the thin disk, thick disk, and halo of the Milky Way. The relative ages of the thin disk, thick disk, and halo will reveal the physical processes responsible for their formation. In addition, it will enable the isolation of the oldest stars in the Milky Way at all metallicities.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.