Using APOGEE Chemical Abundances to Probe Formation Scenarios of the Milky Way Bulge

Sten Hasselquist被授予美国国家科学基金会天文学和天体物理学奖学金，以在犹他大学开展一项研究和教育项目。利用阿帕奇点天文台星系演化实验(APOEE)观测到的数千颗恒星的高质量光谱，哈塞尔奎斯特将对银河系中央隆起进行详细的化学分析。由于中心凸起似乎是大多数盘状星系的一个特征，了解我们星系的凸起是如何形成和演化的，将使天文学家能够了解整个宇宙中星系的形成和演化是如何发生的。除了这项研究，哈塞尔奎斯特还将开发和运营一个基于探究的高空气球项目，目标是来自科学界代表性不足群体的高中生。哈塞尔奎斯特将分析远地点提供的每种元素的平均化学丰度轨迹如何比较银河系凸起和内盘之间的差异。他将探索N维空间中的化学丰度关联，分析这些关联在凸起和内盘之间有何不同。通过这些分析，可以得出关于凸起形成机理的结论。他还将通过调用聚类算法来量化贫金属凸起与银河系光晕或卫星群之间的化学丰度相似性，从而确定凸起中贫金属恒星的来源。此外，他将使用碳氮丰度比为银河系的恒星分配一个化学钟，以便深入研究银河系隆起的化学丰度模式，并增加一个在大规模化学演化研究中通常不存在的时间维度。哈塞尔奎斯特将与主办机构的推广机构合作，创建一个项目，让高中生通过设计和执行高空气球实验来回答特定的科学问题，从而获得宝贵的批判性思维技能。该奖项反映了NSF的法定使命，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。

Sten Hasselquist is awarded an NSF Astronomy and Astrophysics Fellowship to conduct a program of research and education at the University of Utah. Using high quality spectra of thousands of stars observed with the Apache Point Observatory Galactic Evolution Experiment (APOGEE), Hasselquist will perform a detailed chemical analysis of the Milky Way's central bulge. Because a central bulge seems to be a feature of most disk galaxies, understanding how the bulge of our galaxy formed and evolved will allow astronomers to understand how galaxy formation and evolution occurs across the Universe. Alongside this research, Hasselquist will develop and run an inquiry-based high-altitude balloon program targeted at high school students from groups that are underrepresented in science. Hasselquist will analyze how the mean chemical abundance tracks for each element provided by APOGEE compare between the Milky Way's bulge and inner disk. He will explore chemical abundance correlations in N-dimensional space, analyzing how these correlations differ between bulge and inner disk. From these analyses, conclusions can be drawn about formation mechanisms of the bulge. He will also identify the origin of metal-poor stars in the bulge by invoking clustering algorithms to quantify chemical abundance similarities between the metal-poor bulge and the Milky Way's halo or satellite populations. Additionally, he will use carbon-to-nitrogen abundance ratios to assign a chemical clock to the Galaxy's stars, allowing for an in-depth study of the chemical abundance patterns of the Galaxy's bulge with an added time dimension that is not typically available in large-scale chemical evolution studies. Working with outreach facilities at his host institution, Hasselquist will create a program in which high school students gain valuable critical thinking skills by designing and executing high-altitude balloon experiments to answer specific scientific questions.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.