A Green Bank Telescope Survey of Large Galactic H ii Regions
A Green Bank Telescope Survey of Large Galactic H ii Regions
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DOI：
10.3847/1538-4365/aa956a
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
L. Anderson;W. Armentrout;M. Luisi;T. Bania;D. Balser;T. Wenger
中科院分区：
文献类型：
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作者：
L. Anderson;W. Armentrout;M. Luisi;T. Bania;D. Balser;T. Wenger
作为我们正在进行的H II区域发现调查(HRDS)的一部分，我们报告了绿岸望远镜在射电复合线(RRL)发射中探测到148个新的大角度星系H II区域。我们的目标位于赤经，这对应于At。所有的源都选自星系H II区的广域红外勘测探测器星表，并且都有红外角直径。这些“大的”HⅡ区的银河系分布与之前已知的银河系H II区的样本相似。与以往的HRDS调查相比，大的HⅡ区RRL谱线宽度和峰值强度分布偏向较低的值。我们发现了七个RRL极窄的信号源。如果一半的线宽是由湍流引起的，那么这七个源就有热等离子体温度。这些温度低于对银河系H II区所测得的任何温度，窄线分量可能来自H II区光解离区的部分电离区。我们发现了G039.515+00.511，这是银河系中最明亮的H II区之一。我们还探测到了三个带直径的H II区的RRL发射，使它们成为银河系中已知的物理上最大的H II区之一。这次调查完成了在北部天空的HRDS H II区普查，我们在那里发现了887个H II区，是之前已知的银河系H II区普查的两倍多。
As part of our ongoing H ii Region Discovery Survey (HRDS), we report the Green Bank Telescope detection of 148 new angularly large Galactic H ii regions in radio recombination line (RRL) emission. Our targets are located at a declination of , which corresponds to at . All sources were selected from the Wide-field Infrared Survey Explorer Catalog of Galactic H ii Regions, and have infrared angular diameters . The Galactic distribution of these “large” H ii regions is similar to that of the previously known sample of Galactic H ii regions. The large H ii region RRL line width and peak line intensity distributions are skewed toward lower values, compared with that of previous HRDS surveys. We discover seven sources with extremely narrow RRLs . If half the line width is due to turbulence, these seven sources have thermal plasma temperatures . These temperatures are lower than any measured for Galactic H ii regions, and the narrow-line components may arise instead from partially ionized zones in the H ii region photodissociation regions. We discover G039.515+00.511, one of the most luminous H ii regions in the Galaxy. We also detect the RRL emission from three H ii regions with diameters , making them some of the physically largest known H ii regions in the Galaxy. This survey completes the HRDS H ii region census in the Northern sky, where we have discovered 887 H ii regions and more than doubled the size of the previously known census of Galactic H ii regions.