A Pioneering Test of Stellar Population Complexity Outside the Milky Way

银河系外恒星种群复杂性的开创性测试

• 批准号: 1911129
• 负责人: Gail Zasowski
• 金额: $ 27.66万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1911129&HistoricalAwards=false
• 关键词: Pioneering; Test; Stellar; Population; Complexity

The investigator will test the uniqueness of the Milky Way Galaxy's chemical composition. Their goal is understanding how other galaxies change with time, based on observations of stars in the Milky Way (MW). Observations of individual stars in the MW show that the chemistry and the motions of stars are related. These relationships have guided our understanding of how other galaxies change over time and chemically enrich the Universe. Studying the changes in other galaxies over time is extremely difficult. The project team will pioneer new techniques for testing if these patterns occur in the Andromeda Galaxy, the nearest galaxy that is similar to the MW. These measurements will provide insight into that galaxy's history, the uniqueness of the MW, and the usefulness of these systems for tracing how galaxies have grown since the Big Bang. To analyze existing high-resolution, near-infrared (NIR) spectra spanning a large fraction of Andromeda's bulge and disk, the project team will first construct a library of Simple Stellar Population (SSP) models based on theoretical isochrones and nearly 400,000 stellar spectra observations. The public release of this NIR library will fill a gap in the suite of SSP libraries available to the community.The project team will apply this library in two approaches to modeling the Andromeda integrated spectra, one using multi-component spectral fitting and one using machine learning with the SSP models as a training set. The comparison of the two approaches will be used to evaluate the consistency and robustness of the results in different parts of the galaxy. This program will constrain the presence of overlapping stellar populations in the inner regions of Andromeda with distinct dynamical and chemical properties that reflect their diverse histories, information that previously has been measured only in the MW. By revealing how similar Andromeda is to the MW in this important regard, this project will clarify to what extent our high-resolution picture of the MW can be applied to interpreting the unresolved starlight in other galaxies. More generally, these results will test theories of bulge and inner disk evolution and how that evolution is reflected in the constituent stellar populations.This program also supports efforts to promote scientific literacy to two important groups local to the project team: Utah's refugee community and visitors to Utah's national parks. The team will develop astronomy-themed workshops as part of an after-school program that helps middle- and high-school students from refugee families integrate into American classrooms and find social support. These workshops will promote positive perceptions of science and teach critical thinking, communication, and computational skills to students who face unique challenges to their education because of their family histories. The project also includes an extension of a high-impact outreach internship program to bring astronomy education to about 18,000 visitors at Bryce Canyon National Park. These two efforts will be linked by a visit of students from the refugee community to Bryce Canyon for an immersive outdoor experience under some of the US's darkest skies.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.

研究人员将测试银河系化学成分的独特性。 他们的目标是根据对银河系（MW）恒星的观测，了解其他星系如何随时间变化。对MW中单个恒星的观测表明，恒星的化学和运动是相关的。这些关系指导了我们对其他星系如何随时间变化以及如何在化学上丰富宇宙的理解。研究其他星系随时间的变化是非常困难的。该项目团队将开创新技术，以测试这些模式是否发生在仙女座星系中，仙女座星系是与MW相似的最近星系。这些测量将提供深入了解该星系的历史，MW的独特性，以及这些系统在追踪自大爆炸以来星系如何成长方面的有用性。 为了分析现有的高分辨率，近红外（NIR）光谱跨越仙女座的凸起和磁盘的很大一部分，项目团队将首先构建一个基于理论等时线和近40万恒星光谱观测的简单恒星种群（SSP）模型库。该近红外库的公开发布将填补SSP库套件中的空白。项目团队将采用两种方法应用该库对仙女座综合光谱进行建模，一种是使用多组分光谱拟合，另一种是使用机器学习，SSP模型作为训练集。这两种方法的比较将用于评估银河系不同部分结果的一致性和稳健性。该计划将限制仙女座内部区域重叠的恒星种群的存在，这些恒星种群具有独特的动力学和化学性质，反映了它们不同的历史，这些信息以前只在MW中测量。通过揭示仙女座在这一重要方面与MW的相似程度，该项目将澄清我们的MW高分辨率图像在多大程度上可以用于解释其他星系中未解决的星光。更一般地说，这些结果将测试膨胀和内部盘演化的理论，以及这种演化如何反映在组成恒星的种群中。该计划还支持努力促进项目团队当地的两个重要群体的科学素养：犹他州的难民社区和犹他州国家公园的游客。该团队将开发以天文学为主题的研讨会，作为课后计划的一部分，帮助来自难民家庭的初中和高中学生融入美国课堂并寻求社会支持。这些研讨会将促进科学的积极看法，并教批判性思维，沟通和计算技能的学生谁面临独特的挑战，他们的教育，因为他们的家庭历史。该项目还包括扩大一个高影响力的外联实习计划，为布莱斯峡谷国家公园的约18，000名游客提供天文学教育。这两项工作将通过来自难民社区的学生访问布莱斯峡谷，在美国最黑暗的天空下进行身临其境的户外体验而联系起来。该奖项反映了NSF的法定使命，并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，被认为值得支持。

项目成果

The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated-light Spectroscopy

• DOI: 10.3847/1538-4357/acd9a9
• 发表时间: 2023-04
• 期刊: The Astrophysical Journal
• 作者: B. J. Gibson;G. Zasowski;A. Seth;Aishwarya Ashok;Kameron Goold;T. Wainer;S. Hasselquist;J. Holtzman;J. Imig;D. Bizyaev;S. Majewski

The APOGEE Library of Infrared SSP Templates (A-LIST): High-resolution Simple Stellar Population Spectral Models in the H Band

• DOI: 10.3847/1538-3881/abd7f1
• 发表时间: 2020-12
• 期刊: The Astronomical Journal
• 作者: Aishwarya Ashok;G. Zasowski;A. Seth;S. Hasselquist;Galen J. Bergsten;Olivia R. Cooper;N. Boardman;D. Bizyaev;Sofia Meneses Goytia;D. A. García-Hernández;A. Roman-Lopes