Proper Motion of the Andromeda Galaxy: The Key to Local Group Masses and Dynamics

这个为期三年的项目提供仙女座星系（M31）水脉泽的天体测量，仙女座星系是本星系群中银河系的大型伴旋星系。大麦哲伦云和小麦哲伦云（LMC和SMC）以及M33的自行已经或多或少有足够的精确度，但是M31及其许多矮伴星和恒星流的自行是拼图中缺失的一块。M31的自行测量对于更好地了解本星系群的暗物质分布和运动学是必要的。这些测量可以预期对星系研究产生更大的影响，因为它们限制了本星系群的形成和历史以及未来演化的模型。观测使用了甚长基线阵列、扩展甚大阵列和高灵敏度阵列的新功能。这项工作的更广泛影响还包括培训新的观察员使用国家科学基金会支持的设施。PI将他的研究成果融入课堂，并致力于开发旨在改变各级教学天文学课程的工具和技术。该计划将把三门课程从传统的讲座转变为问题讨论辅导课程。

This three-year project provides astrometry of water masers in the Andromeda Galaxy (M31), the large companion spiral galaxy to the Milky Way in the Local Group of galaxies. The proper motion of the Large and Small Magellanic Clouds (LMC, and SMC) and M33 are already known with more or less adequate accuracy, but the proper motion of M31 and its many dwarf companions and stellar streams is the missing piece in the puzzle. The proper motion measurement of M31 is necessary to get a better understanding of the dark matter distribution and kinematics of the Local Group. The measurements can be expected to have a larger impact on galactic research because they constrain models of the formation and history, but also future evolution, of the Local Group of galaxies. The observations use new capabilities of the Very Long Baseline Array, Expanded Very Large Array, and High Sensitivity Array. The broader impacts of this work further include training new observers to use NSF-supported facilities. The PI integrates results from his research into the classroom and works on tools and techniques aimed to transform astronomy courses at all levels of instruction. This program will transform three courses spanning the range of instruction level from traditional lectures into question-discussion-tutorial sessions.