Collaborative Proposal: Resolving Physical Conditions of Diffuse Ionized Gas throughout the Milky Way-Magellanic System

恒星诞生的气体云向我们展示了恒星对周围环境的巨大影响。恒星的紫外线从原子中剥离电子，使它们电离。这些自由电子最终会再次与原子结合，并释放出能说明问题的颜色。在过去的几十年里，威斯康辛州的H-Alpha绘图仪（WHAM）发现，整个天空都在由遍布银河系的电离氢原子发出的红光中微微发光。WHAM小组一直在整个银河系及其邻近的卫星星系麦哲伦星云中探索这种“漫射电离气体”。WHAM可以揭示比猎户座星云暗淡近1亿倍的辐射。WHAM仍然是世界上最灵敏的仪器之一，用于研究天空中微弱的漫射光。该团队正在开发一个新的展览和教育活动，这将有助于展示科学家如何使用光谱学来识别元素和探索遥远物体的特性。该展览将吸引公众和学生团体使用与WHAM相同的Fabry-Perot技术。研究人员将继续为本科生和研究生提供极好的机会。在之前由美国国家科学基金会资助的研究中，WHAM的研究人员首次对银河系和麦哲伦星云中的扩散电离气体进行了追踪。这些努力补充了对氢的无线电调查，追踪其较冷的中性阶段。现在，从我们所在的银河系的各个方向都可以探测到中性氢和电离氢的发射。有了这个奖项，研究人员利用WHAM开始了一个多样化的观察项目。通过捕捉其他元素的辐射，他们追踪整个扩散气体的温度和电离程度。这项新研究推进了我们对星际物质的理解，它的形成过程，以及恒星如何影响我们的银河系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Clouds of gas, where stars are born, show us the spectacular impact of stars on their immediate surroundings. The stars’ ultraviolet light strips electrons from atoms, ionizing them. These free electrons eventually combine again with atoms and emit telltale colors. Over the last few decades, the Wisconsin H-Alpha Mapper (WHAM) discovered that the entire sky is glowing faintly in red light emitted by ionized hydrogen atoms that pervade the Milky Way. The WHAM group has been exploring this "diffuse ionized gas" throughout the Milky Way and its neighboring satellite galaxies, the Magellanic Clouds. WHAM can reveal emission nearly a 100-million times fainter than the Orion Nebula. WHAM remains one of the most sensitive instruments in the world for studying faint, diffuse light in our sky. The Team is developing a new exhibit and educational activities that will help show how scientists use spectroscopy to identify elements and explore the properties of distant objects. The exhibit will engage the public and student groups with the same Fabry-Perot technology used by WHAM. The investigators will continue to provide excellent opportunities for undergraduate and graduate students.During previous NSF-funded studies, WHAM investigators produced the first surveys that traced diffuse ionized gas in the Milky Way and the Magellanic Clouds. These efforts complement radio surveys of hydrogen that trace its cooler, neutral phase. Neutral and ionized hydrogen emission are now detected in every direction from our location inside the Galaxy. With this award, the investigators use WHAM to embark on a diverse observational program. Capturing emission from other elements, they are tracing the temperature and degree of ionization throughout the diffuse gas. This new study advances our understanding of interstellar matter, the processes that shape it, and how stars affect our Galaxy.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.