The H3 Spectroscopic Survey and the Origin of the Galaxy

我们银河系的一个主要组成部分是它的恒星晕，这是一种球状分布的恒星，比星盘延伸10倍。星系形成理论预测，我们银河系的恒星晕是由较小星系的“粉碎”形成的。然而，这一理论尚未在观测上得到证实。在这个项目中，研究人员将测量星晕中30万颗恒星的基本恒星性质(速度、距离和“化学”)。有了这些数据，他们将提供构成我们恒星晕的构件的完整清单。作为该项目的一部分进行测量的恒星年龄将被用来推断恒星形成和星系合并事件的时间表。最后，研究人员将利用这些观测结果来预测银河系最大的卫星伴星--大麦哲伦星云--对星晕的影响。这样的观测可能会提供对暗物质和引力本质的独特洞察。在教育方面，该项目将支持一名研究生，他们将接受恒星光谱分析和动力学模型在银河系中的应用方面的培训。作为班纳克学院的一部分，该项目还将支持对来自任职人数不足背景的暑期本科生的培训。班纳克研究所有一个暑期项目，旨在培养学生的研究技能和社会正义教育。“高分辨率光晕中的Hectochelle”(H3)调查将提供北半球高纬度区域恒星的高分辨率光谱，以测量径向速度、分光光度距离、[Fe/H]和[α/Fe]相对丰度。确定这些参数将被用来解释相+化学空间中结构的起源。这些观测将对银河系的组装历史、外银河系质量轮廓的测量、原地恒星晕的起源进行详细的约束，并将对各种有趣的、稀有的群体敏感，例如化学上特殊的恒星和高速恒星。这一奖项反映了美国国家科学基金会的法定任务，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A main component of our Milky Way galaxy is its stellar halo, a spherical distribution of stars extending 10 times further than the stellar disk. Galaxy formation theories predict that our Milky Way's stellar halo was formed from "shredding" of smaller galaxies. However, this theory has not yet been confirmed observationally. In this project the investigators will measure the basic stellar properties (velocities, distances, and "chemistry") of 300,000 stars in the stellar halo. With these data they will provide a full inventory of the building blocks that formed our stellar halo. Stellar ages, which are measured as part of this project, will be used to deduce the timeline of star formation and galaxy merger events. Finally, the investigators will use these observations to predict the effect of the Milky Way's largest satellite companion, the Large Magellanic Cloud, on the stellar halo. Such observations may provide unique insight into the nature of dark matter and gravity. Educationally, this project will support a graduate student who will be trained on the analysis of stellar spectra and the application of dynamical models to the Galaxy. The project will also support the training of summer undergraduates from under-represented backgrounds as part of the Banneker Institute. The Banneker Institute has a summer program aimed at developing students’ research skills and social justice education.The “Hectochelle in the Halo at High Resolution” (H3) Survey will deliver high resolution spectra of stars in high Galactic latitude fields in the Northern hemisphere to measure radial velocities, spectrophotometric distances, [Fe/H], and [alpha/Fe] relative abundances. Determining these parameters will be used to explain the origin of structures in phase plus chemistry space. These observations will enable detailed constraints on the assembly history of the Galaxy, measurements of the mass profile of the outer Galaxy, the origin of the in-situ stellar halo, and will be sensitive to a variety of interesting, rare populations such as chemically peculiar stars and high velocity stars.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.