Ultra- and hyper-compact H ii regions at 20 GHz
Ultra- and hyper-compact H ii regions at 20 GHz
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DOI：
10.1111/j.1365-2966.2010.16589.x
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发表时间：
2010-02
影响因子：
4.8
通讯作者：
T. Murphy;M. Cohen;R. Ekers;A. Green;R. Wark;Vanessa Moss The University of Sydney;U. California;Berkeley;The Australia Telescope National Facility
中科院分区：
文献类型：
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作者：
T. Murphy;M. Cohen;R. Ekers;A. Green;R. Wark;Vanessa Moss The University of Sydney;U. California;Berkeley;The Australia Telescope National Facility
我们对银河系南部平面的4个超紧凑HII区域和4个超紧凑HII区域进行了射电和红外观测。这些天体是从UCHII区域的盲测中选择的，该盲测使用了两次新的南部天空射电调查的数据；澳大利亚望远镜20 GHz巡天（AT20G）和第二代莫隆洛银河面巡天（MGPS-2） 843 MHz。据我们所知，这是首次对超紧凑和超紧凑HII区域进行盲测。我们用澳大利亚望远镜紧凑型阵列跟踪这些源，获得了H70°复合线测量值、20 GHz更高分辨率图像以及30、40和95 GHz通量密度测量值。由此，我们确定了尺寸和复合线温度，并对光谱能量分布进行建模，以确定发射措施。与文献中的基准参数相比，我们根据其物理参数将源分类为超紧凑或超紧凑。这些明亮、紧凑的光源中有几个是普朗克卫星任务的低频仪器（30 - 70 GHz）和高频仪器100 GHz频道的潜在校准器。它们也可以用作澳大利亚望远镜紧凑阵列的校准器，该阵列在更高频率和银道面区域缺乏良好的非可变主通量校准器。我们的光谱能量分布允许确定普朗克波段内的通量密度，尽管我们的高频观测表明，一些源在95千兆赫（3毫米）处有过量的发射，这是当前模型无法解释的。
We present radio and infrared observations of 4 hyper-compact HII regions and 4 ultracompact HII regions in the southern Galactic plane. These objects were selected from a blind survey for UCHII regions using data from two new radio surveys of the southern sky; the Australia Telescope 20 GHz survey (AT20G) and the 2nd epoch Molonglo Galactic Plane Survey (MGPS-2) at 843 MHz. To our knowledge, this is the first blind r adio survey for hyper- and ultra-compact HII regions. We have followed up these sources with the Australia Telescope Compact Array to obtain H70� recombination line measurements, higher resolution images at 20 GHz and flux density measurements at 30, 40 and 95 GHz. From this we have determined sizes and recombination line temperatures as well as modeling the spectral energy distributions to determine emission measures. We have classified the sources as hyper-compact or ultra-compact on the basis of their physical parameters, in comparison with benchmark parameters from the literature. Several of these bright, compact sources are potential cali brators for the Low Frequency Instrument (30 70 GHz) and the 100-GHz channel of the High Frequency Instrument of the Planck satellite mission. They may also be useful as calibrators for the Australia Telescope Compact Array, which lacks good non-variable primary flux ca librators at higher frequencies and in the Galactic plane region. Our spectral energy distri butions allow the flux densities within the Planck bands to be determined, although our high frequency observations show that several sources have excess emission at 95 GHz (3 mm) that can not be explained by current models.