磁场和PDR的位置
Magnetic fields and the location of the PDR
摘要：
我回顾了最近的研究猎户座和M17的发射线区域。两者都有相似的几何形状，一个围绕着中央星团的热冲击气体泡，带有H^+、H^0和H_2区域，通常被称为H II区域、PDR和分子云，在分子云表面形成连续的壳层。用21 cm塞曼极化测量了H^0区的磁场，发现它比扩散ISM中的磁场强1 - 2倍。这些区域似乎处于大致的流体静力平衡状态。H^+区域被星光辐射压推离星团。由于大多数星光都是电离辐射，因此它的大部分向外推力将作用在H^+区域，然后作用在H^0区域。H^0区的磁压平衡了星光中的动量，它们共同确定了H^0区的位置。这幅图像是，当星团形成时，它产生了一个电离气体泡，这些气体泡在H^0和H_2区域周围膨胀和压缩。磁场被放大，直到它的压力能够支持星光中的动量。这为理解为PDR模型建立参数的基础物理提供了极大的简化。
英文摘要：
I review recent studies of the emission-line regions in Orion and M17. Both have similar geometries, a bubble of hot shocked gas surrounding the central star cluster, with H^+, H^0, and H_2 regions, often referred to as H II regions, PDRs, and molecular clouds, forming successive shells on the surface of a molecular cloud. The magnetic fields in the H^0 regions have been measured with 21 cm Zeeman polarization and are found to be 1 -- 2 dex stronger than the field in the diffuse ISM. The regions appear to be in rough hydrostatic equilibrium. The H^+ region is pushed away from the star cluster by starlight radiation pressure. Since most starlight is in ionizing radiation, most of its outward push will act on the H^+ region and then on to the H^0 region. The magnetic pressure in the H^0 region balances the momentum in starlight and together they set the location of the H^0 region. The picture is that, when the star cluster formed, it created a bubble of ionized gas which expanded and compressing surrounding H^0 and H_2 regions. The magnetic field was amplified until its pressure was able to support the momentum in starlight. This offers a great simplification in understanding the underlying physics that establishes parameters for PDR models.
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。
