Collaborative Research: Distances to High Velocity Clouds

这项合作奖将资助一个测量到银河系高速云团(HVC)距离的项目的继续，HVC是由中性氢气组成的巨大云团，其运动速度与银河系差分旋转的简单模型不相容。由于它们从银河系盘中的气体中脱颖而出，它们可以被用作银河系中高能现象的测试粒子。该计划将利用投射在云层上的恒星光谱中的星际吸收线来研究HVC金属含量和距离。这个项目的结果对于估计银河系演化的几个基本参数将是重要的，包括低金属丰度气体的流入速率，暗物质晕势，气体在盘和晕之间的循环速率，以及脱离盘的电离光子的比例。这个项目的更广泛的影响包括研究生和本科生的培训。

This collaborative award will fund continuation of a project to measure distances to the Galactic high velocity clouds (HVCs), massive clouds of neutral hydrogen gas moving at velocities incompatible with a simple model of differential galactic rotation. Since they stand out from the gas in the Galactic Disk, they can be used as test particles for energetic phenomena in the Milky Way. The program will study HVC metallicities and distances using interstellar absorption lines in the spectra of stars projected against the clouds. The results of this project will be important for estimates of several fundamental parameters of Galactic evolution, including the rate of infall of low metallicity gas, the potential of the dark matter halo, the rate of circulation of gas between Disk and Halo, and the fraction of ionizing photons escaping the Disk.The Broader Impacts of this program include training of graduate and undergraduate students.