M101中由多颗超新星抽空的膨胀中性氢超壳层
An Expanding Neutral Hydrogen Supershell Evacuated by Multiple Supernovae in M101
摘要：
在银河系和其他邻近的恒星形成星系中已经发现了几个中性氢（HI）空洞。有人认为，其中至少有一小部分可能是膨胀的超壳层，由发生在OB协会中的多颗超新星的联合机械反馈驱动。然而，大多数河外HI洞既没有证实的膨胀速度，也没有确定的OB协会在他们内部。在这项工作中，我们报告了在附近的旋涡星系M101中发现的一个完整的膨胀HI超壳层，其中有一个UV发射OB协会。我们测量了它的大小（500 pc）和膨胀速度（20 km/s）通过识别其接近和后退分量的位置-速度空间，使用21 cm发射光谱。这为我们提供了一个理想的系统来测试由多颗超新星的机械反馈驱动的超壳层理论。超壳层内的集群的紫外线辐射与模拟的光谱能量分布的合成集群的适当年龄（~15百万年）进行了比较。观测到的紫外线通量与超壳层能量收支所需的适当质量（~10^5太阳质量）和年龄相一致。这个超壳层和另一个先前报道的在同一个星系的属性被用来推断其中性氢标度高度和平均中性氢密度的磁盘。另一个紫外线发射恒星协会的存在下，在过密的扫起气体的传播恒星形成的背景下进行了讨论。
英文摘要：
Several neutral hydrogen (HI) cavities have been detected in the Milky Way and other nearby star forming galaxies. It has been suggested that at least a fraction of them may be expanding supershells driven by the combined mechanical feedback from multiple supernovae occurring in an OB association. Yet most extragalactic HI holes have neither a demonstrated expansion velocity, nor an identified OB association inside them. In this work, we report on the discovery of an unbroken expanding HI supershell in the nearby spiral galaxy M101, with an UV emitting OB association inside it. We measure its size (500 pc) and expansion velocity (20 km/s) by identifying both its approaching and receding components in the position-velocity space, using 21 cm emission spectroscopy. This provides us with an ideal system to test the theory of supershells driven by the mechanical feedback from multiple supernovae. The UV emission of the cluster inside the supershell is compared with simulated spectral energy distribution of synthetic clusters of the appropriate age (~15 Myr). The observed UV flux is found to be consistent with an association of the appropriate mass (~10^5 Solar Mass) and age required by the energy budget of the supershell. Properties of this supershell and another previously reported in the same galaxy are used to infer its neutral hydrogen scale height and mean neutral hydrogen density in the disk. The presence of another UV emitting stellar association in over-dense swept up gas is discussed in the context of propagating star formation.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
