RUI: The Survey of HI in Extremely Low-mass Dwarfs (SHIELD)

星系最初是如何形成的，以及它们在整个生命周期中是如何变化的，这是天体物理学中最不为人所知的问题之一。许多项目都以解开这些谜团为中心。该项目旨在表征极低质量矮星系的气体和恒星成分，这对我们理解气体在浅重力势井中转化为恒星的过程至关重要。该项目将对最近ALFALFA（阿雷西博遗产快速ALFA[阿雷西博l波段馈源阵列]）目录中选择的12个极低质量星系进行全面的多波长调查。这个项目调查的基础是所有12个星系的深原子氢（HI）光谱线成像，这是用最近扩大的Jansky甚大阵列（JVLA），一个由nsf资助的设施。各种设施（包括GALEX卫星，哈勃太空望远镜，斯皮策太空望远镜，WIYN天文台和基特峰国家天文台）的丰富配套观测将允许探索对我们理解星系演化至关重要的多个科学主题。具体来说，首席研究员（PI）已经着手解决以下问题：(1)在迷你光晕、非常低质量的矮星和更大质量的系统之间有什么性质的变化？(2)低质量矮星的重子质量占比是多少？(3)在非常低质量的星系中，恒星形成过程的特征是否不同？在教育方面，PI将让本科生参与前沿研究。这项教育和培训将针对马卡莱斯特学院的三个学生群体。第一个目标人群是参加观测天文学课程的高级物理和天文学专业学生；这些学生将在射电天文学技术方面获得严格的理论背景，并通过参与本项目进行研究性学习。第二个目标人群是暑期研究助理，通常是即将升入大三或大四的物理和天文学专业的学生，他们将处理为本项目获得的数据。这些为期10周的约会使学生们能够深入了解天体物理学研究，并为研究生学习的挑战做好准备。第三个目标人群是学士学位后的研究助理。这个越来越受欢迎的职业轨道允许学生在完成本科学习之后，在进入研究生院之前，花一年的时间从事全职研究。“post- back”获得了独特的教育体验，同时保证了科学项目的进步。各级本科学生将通过在专题会议上发言和在天体物理学文献中发表文章的方式向社会传播科学成果。

Precisely how galaxies initially form and how they change throughout their lifetimes are among the least understood problems in astrophysics. Many projects are centered on unraveling these mysteries. This project aims to characterize the gaseous and stellar components of extremely low-mass dwarf galaxies, which is critical for our understanding of the processes by which gas is converted into stars in shallow gravitational potential wells. The project will conduct a comprehensive, multi-wavelength survey of 12 extremely low-mass galaxies selected from the recent ALFALFA (Arecibo Legacy Fast ALFA [Arecibo L-band Feed Array]) catalogue. The cornerstone of this project's survey is deep atomic hydrogen (HI) spectral line imaging of all 12 galaxies with the recently expanded Jansky Very Large Array (JVLA), an NSF-funded facility. A rich suite of supporting observations with various facilities (including the GALEX satellite, the Hubble Space Telescope, the Spitzer Space Telescope, the WIYN observatories, and the Kitt Peak National Observatory) will allow the exploration of multiple science themes that are critical to our understanding of galaxy evolution.Specifically, the principal investigator (PI) has set out to address the following questions: (1) What properties change between mini-halos, very low-mass dwarfs, and more massive systems? (2) What fraction of the mass in low-mass dwarfs is baryonic? (3) Is the character of the star formation process different in very low-mass galaxies?Educationally, the PI will engage undergraduate students in forefront research. This education and training will target three student populations at Macalester College. The first target population is the upper-level physics and astronomy major enrolled in the Observational Astronomy course; these students will obtain a rigorous theoretical background in radio astronomy techniques and exposure to research-based learning via their involvement with this project. The second target population is the summer research associate, typically a rising junior or senior physics and astronomy major who will work on the data acquired for this project. These 10-week appointments allow students to obtain a deep immersion in astrophysical research and prepare them for the challenges of graduate study. The third target population is the post-baccalaureate research associate. This increasingly popular career track allows students to spend a year engaged in full-time research after the completion of their undergraduate studies but prior to entering graduate school. The "post-bac" attains a unique educational experience while assuring the forward progress of the science program. Undergraduate students at all levels will disseminate science results to the community by presenting at topical meetings and by publishing in the astrophysical literature.