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arXiv 1002.4627astro-ph.GA
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超紧凑和超紧凑HII区域，20 GHz

Ultra- and Hyper-compact HII regions at 20 GHz

Tara Murphy, Martin Cohen, Ronald D. Ekers, Anne J. Green, Robin Wark, Vanessa Moss

备注：
13 pages, 7 figures, accepted for publication in MNRAS
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摘要：

我们目前的无线电和红外观测的4个超紧凑的HII区和4个超紧凑的HII区在南银道面。这些天体是从UCHII区域的盲测中选出的，盲测使用的数据来自两个新的南部天空无线电巡天;澳大利亚望远镜20 GHz巡天（AT 20 G）和843 MHz的第二纪元Molonglo银道巡天（MGPS-2）。据我们所知，这是第一次对超紧凑和超紧凑的HII区域进行盲无线电调查。我们已经跟进这些来源与澳大利亚望远镜紧凑阵列获得H70-α复合线测量，更高分辨率的图像在20 GHz和通量密度测量在30，40和95 GHz。由此，我们确定了尺寸和复合线温度，以及建模的光谱能量分布，以确定发射措施。我们已经分类为超紧凑或超紧凑的物理参数的基础上，与基准参数从文献中的源。这些明亮、紧凑的光源中有几个是普朗克卫星任务高频仪器低频仪器（30-70 GHz）和100 GHz通道的潜在校准器。他们也可能是有用的校准器的澳大利亚望远镜紧凑型阵列，其中缺乏良好的不可变的初级通量校准器在较高的频率和在银河平面区域。我们的光谱能量分布允许普朗克带内的通量密度被确定，虽然我们的高频观测表明，几个源在95 GHz（3 mm），不能用当前的模型解释过量的发射。

英文摘要：

We present radio and infrared observations of 4 hyper-compact HII regions and 4 ultra-compact 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 radio survey for hyper- and ultra-compact HII regions. We have followed up these sources with the Australia Telescope Compact Array to obtain H70-alpha 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 calibrators 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 calibrators at higher frequencies and in the Galactic plane region. Our spectral energy distributions 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.

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