New Frontiers in Stellar Astrophysics: Massive Stars as Cosmological Tools

质量是太阳10倍以上的恒星是我们宇宙的重要组成部分。它们在超新星爆炸中剧烈死亡，在超新星爆炸中，恒星无法抵抗重力，释放新的物质到星系中形成新的恒星。这些大质量恒星非常明亮，因此它们有望作为遥远星系的距离估算器。如果我们知道一颗恒星应该有多亮，我们就可以比较它的视亮度来找到它的距离。不幸的是，这些恒星非常罕见，因此目前人们对它们知之甚少。研究人员计划收集其他星系中大质量发光恒星的基本数据。这些观测将帮助我们更好地了解这些恒星的生命。研究生和本科生都将参与研究。她还将与Zooniverse项目合作，将天体的光变化（通常是视觉上的）转换为声音。这一努力将引起公民科学家的兴趣，特别是那些视力受损的科学家。研究人员描述了一个多波长观测计划，该计划涵盖了恒星爆炸成为超新星之前恒星演化的后主序阶段。正在进行的HST COS远紫外SNAP计划提供了高信噪比光谱，分辨率比以前更好。该项目将对不同金属丰度的物体进行取样，包括极贫金属的星系，它们将作为早期宇宙中恒星形成区域的类似物。研究人员还将通过对87个附近恒星形成星系的观测，建立一个全面的紫外光谱库，利用这些数据来测试下一代恒星群合成和光电离代码。

Stars more than 10 times as massive as the Sun are important building blocks in our Universe. Their violent deaths in supernova explosions, in which stars are unable to hold themselves up against gravity, release new material into galaxies to form new stars. These massive stars are bright, and thus they hold promise as distance estimators to distant galaxies. If we know how bright a star should look, we can compare its apparent brightness to find its distance. Unfortunately, these stars are rare and thus poorly understood at the moment. The investigator plans to collect basic data about massive, luminous stars in other galaxies. The observations will help us better understand the lives of these stars. Both graduate and undergraduate students will take part in the research. She will also work with the Zooniverse Project to convert the light variations of astronomical objects---usually conveyed visually---to sound. This effort will be of interest to citizen scientists, particularly those who are visually impaired.The investigator describes a multi-wavelength observing plan that covers the post-main sequence phases of stellar evolution before the stars explode as supernovae. The ongoing HST COS far-UV SNAP program provides high S/N spectra, with better resolution, than were previously possible. The project will sample objects of different metallicity, including extremely-metal-poor galaxies, that will serve as analogs for star formation regions in the early Universe. The investigator will also create a comprehensive library of ultraviolet spectra using observations of 87 nearby star-forming galaxies, using these data to test the next generation of stellar population synthesis and photoionization codes.