Diffuse Ionized Gas in Galactic Halos: Multiwavelength Studies of the Milky Way and Magellanic System with WHAM-South

这个更新项目是为了使用威斯康星H-Alpha绘图仪（WHAM）完成对银河系电离气体区域在本地宇宙中的分布和运动学的第一个全面视图，这是一个远程控制的法布里-佩罗天文设施。WHAM从微弱的漫射源收集高分辨率的发射光谱，其聚焦设计灵敏，可以探测到比猎户座星云暗淡近1亿倍的发射。随着仪器在智利Cerro Tololo的新位置，研究人员可以瞄准区域来确定银河系南部天空中扩散电离气体的分布和物理特性。研究人员完成了对银河系巴尔默α (h - α)氢发射线的第一次系统光谱调查。这次巡天提供了电离气体的敏感视图，发现了明亮、离散的H II区与大细丝、气泡和贝壳交织在一起，并揭示了在整个天空中发现的一个微弱的、普遍存在的背景，称为热电离介质（WIM）。WHAM的新视图包括银河系内部恒星形成区域上方最明亮的扩展发射区域之一，以及我们天空中最大的弥散H II区域之一。光谱用于研究局部电离区域和银河系大区域内气体的电离分布和温度。在大尺度结构中，发射区域的速度和电离气体与附近热恒星和中性气体的关系可以受到过去和现在相对短寿命的大质量恒星的影响。对复杂区域的研究提供了对银河系盘和晕中的能量传输过程的见解，并追踪了银河系旋臂中活跃恒星的形成，这对精确绘制具有挑战性。WHAM的运动分辨率和多波长能力可以分离出特定的大规模发射特征，这将更好地理解这些特征是如何依赖于环境、金属丰度和本地恒星形成速率的。这项研究将完成对银河系大规模辐射的几项全面的、多线的研究。氮、硫、氧和氦相对于氢的光发射强度取决于气体的组成、温度、加热和电离程度。内星系的热电离介质（WIM）的衍生性质将与外星系的进行比较。另一个目标是研究扩展气体结构的电离成分，如麦哲伦流、桥和麦哲伦系统的前导臂，那里的元素丰度、尘埃含量和辐射场与我们的银河系有很大的不同。这有助于理解这样的电离区域是如何在远离活跃恒星形成的地方维持的，以及电离成分是否包含大量尚未被检测到的质量。WHAM项目为本科生和研究生提供了参与研究级天文台并与之互动的绝佳机会。它有助于远程观测技术的技术进步，以提高数据收集的质量和效率。这些高质量的数据集将为整个天文学界所用。这些观测结果为多相星际介质的大规模MHD模拟提供了重要的方向，在多相星际介质中，ISM物质和能量从恒星之间转移。WHAM在航空学、太阳系天文学、河外天文学和宇宙学等领域做出了贡献。它的高度灵敏度和速度分辨率使研究地球大气、彗星和黄道带尘埃成为可能。为了分析银河系外和宇宙背景，需要了解银河系中微弱但普遍存在的电离气体的完整特征。

This renewal project is for the completion of the first comprehensive view of the distribution and kinematics of the Milky Way's ionized gas regions in the local universe using the Wisconsin H-Alpha Mapper (WHAM), a remotely controlled Fabry-Perot astronomical facility. WHAM collects high-resolution optical emission-line spectra from faint, diffuse sources, and its focused design is sensitive to detect emission nearly a 100 million times fainter than the Orion Nebula. With the instrument's new location on Cerro Tololo in Chile, the investigators can target regions to determine the distribution and physical properties of diffuse ionized gas over the southern sky of the Milky Way. The investigators completed the first systematic spectral survey of the Milky Way in the Balmer-alpha (H-alpha) emission line of hydrogen. This all sky survey provides a sensitive view of ionized gas, and found a mix of bright, discrete H II regions intertwined with large filaments, bubbles, and shells and revealed a faint, pervasive background detected over the whole sky known as the warm ionized medium (WIM).WHAM's new view includes one of the brightest, extended regions of emission above star-forming regions in the inner Galaxy as well as one of the largest diffuse H II regions in our sky. Spectra are used to study the distribution of ionization and temperature of the gas within locally ionized regions and across large regions of the Milky Way. The velocity of emitting regions and the relationship of ionized gas to nearby hot stars and neutral gas in large-scale structures can be influenced by past and present generation of relatively short-lived massive stars. The study of complex regions provides insights to energy transport processes in the Galactic disk and halo and traces active star formation in the Galactic spiral arms, which is challenging to map accurately.WHAM's kinematic resolution and multi-wavelength capability can isolate specific large-scale emission features, which will provide a better understanding how these features depend on environment, metallicity, and local star formation rate. This study will complete several comprehensive, multiline studies of large-scale emission in the Galaxy. The strengths of optical emission from nitrogen, sulfur, oxygen, and helium relative to that of hydrogen depend on the composition, temperature, heating, and ionization of the gas. The derived properties of the warm ionized medium (WIM) in the inner Galaxy will be compared to those in the outer Galaxy. Another goal is to study the ionized component of the extended gaseous structures such as the Magellanic Stream, Bridge, and Leading Arm of the Magellanic System, where elemental abundances, dust content, and radiation fields differ significantly from those in our Galaxy. This helps to understand how such ionized regions can be maintained so far from active star formation and whether the ionized component contains a significant amount of mass that not yet been detected.The WHAM project provides excellent opportunities for undergraduate and graduate students to participate and interact with a research-grade astronomical observatory. It contributes to technological advances in remote observing techniques to improve the quality and efficiency of data collection. The high-quality datasets will be of use by the entire astronomical community. The observations provide essential direction for new, large-scale MHD simulations of a multiphase interstellar medium where ISM matter and energy are transferred to and from stars. WHAM contributes to the fields of aeronomy, solar system astronomy, extragalactic astronomy, and cosmology. Its deep sensitivity and velocity resolution enable studies of the Earth's atmosphere, comets, and zodiacal dust. The full characterization of the faint but pervasive ionized gas in the Galaxy needs to be understood for the analysis of extragalactic and cosmic backgrounds.