人马座B1 --H II区和PhotoDissociation区的拼接
Sagittarius B1 -- A Patchwork of H II Regions and PhotoDissociation Regions
摘要：
Sgr B1是银河系中心的一个明亮的H II区域，紧邻大质量恒星形成的巨大分子云Sgr B2，并且显然由于它们相似的径向速度而与它相连。在2018年，我们从SOFIA FIFI-LS对[O III] 52和88微米线的观测中发现，没有中心激发星团，电离星必须广泛分布在整个区域。在这里，我们提出了SOFIA FIFI-LS观测的[O I] 146和[C II] 158微米线形成在周围的光解离区域（PDR）。我们发现，这些线既不相互关联，也不与[O III]线，但它们一起更好地与来自Hi-GAL的70微米Herschel PACS图像相关。我们由此推断，Sgr B1由一些较小的H II区域加上它们相关的PDR组成，一些看到正面，另一些看到或多或少的边缘。使用模型计算与多云，我们证明了可能出现的边缘上的PDR，并显示PDR密度和电子密度之间的密度差估计从[O III]线的比率是不兼容的压力平衡，除非有一个很大的压力贡献，无论是湍流或磁场或两者兼而有之。我们同样得出结论，激发Sgr B1的热恒星在整个区域中分布广泛，距离气体相当远，没有证据表明目前有大质量恒星形成。
英文摘要：
Sgr B1 is a luminous H II region in the Galactic Center immediately next to the massive star-forming giant molecular cloud Sgr B2 and apparently connected to it from their similar radial velocities. In 2018 we showed from SOFIA FIFI-LS observations of the [O III] 52 and 88 micron lines that there is no central exciting star cluster and that the ionizing stars must be widely spread throughout the region. Here we present SOFIA FIFI-LS observations of the [O I] 146 and [C II] 158 micron lines formed in the surrounding photodissociation regions (PDRs). We find that these lines correlate neither with each other nor with the [O III] lines although together they correlate better with the 70 micron Herschel PACS images from Hi-GAL. We infer from this that Sgr B1 consists of a number of smaller H II regions plus their associated PDRs, some seen face-on and the others seen more or less edge-on. We used the PDR Toolbox to estimate densities and the far-ultraviolet intensities exciting the PDRs. Using models computed with Cloudy, we demonstrate possible appearances of edge-on PDRs and show that the density difference between the PDR densities and the electron densities estimated from the [O III] line ratios is incompatible with pressure equilibrium unless there is a substantial pressure contribution from either turbulence or magnetic field or both. We likewise conclude that the hot stars exciting Sgr B1 are widely spaced throughout the region at substantial distances from the gas with no evidence of current massive star formation.
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