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首页> 外文期刊>The Astrophysical journal >THE H II REGION COMPLEX G5.48-0.24: RADIO CONTINUUM H I, AND CO OBSERVATIONS
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THE H II REGION COMPLEX G5.48-0.24: RADIO CONTINUUM H I, AND CO OBSERVATIONS

机译：H II地区综合体G5.48-0.24：无线电连续体H I和合作观测

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摘要

We have carried out VLA radio continuum (6 and 20 cm), VLA H I 21 cm line, and ~(13)CO J = 1-0 line observations of the Galactic H II region G5.48 -0.24. We present the continuum maps at 21 cm with ～50″ resolution and at 6 and 20 cm with ～ 5″ resolution. The radio continuum maps show that the H n region is composed of a bright component immersed in a diffuse emission of ～6′ (or 21 pc) radius. The bright component has a compact (0.7 pc) core surrounded by an extended (3.4 pc) halo. According to Wood & Church-well (1989), the compact core has an ultracompact (0.04 pc) subcomponent. The rms electron density of the diffuse emission is 7 cm~(-3) and it increases roughly by a factor of 10 from one structure to the next small-scale structure. The observed radio continuum flux, half of which is contributed by the diffuse emission, requires an ionizing star of O5 ZAMS. If we consider the direct absorption of ionizing stellar photons by dust within H n regions, the bright component alone requires an O5 exciting star. The brightness of the diffuse continuum emission decreases steeply along its western boundary and gradually at other directions. The VLA H I 21 cm line maps show that there is an H I cloud in contact with the steep western boundary. The ~(13)CO line observations show that there is a giant molecular cloud associated with the H n region. The bright component of the radio continuum emission coincides with the dense core of the molecular cloud. Therefore, G5.48 -0.24 appears to be an H II region-molecular cloud complex where the formation of massive stars occurred recently. The radio continuum structures of largely different dynamical ages (e.g., 4 x 10~3-2 x 10~6 yr) may indicate that either the sequential star formation is proceeding, or G5.48-0.24 is a blister-type H II region.
机译：我们已经对银河H II区域G5.48 -0.24进行了VLA无线电连续谱（6和20 cm），VLA H I 21 cm线和〜（13）CO J = 1-0线的观测。我们以21厘米（〜50英寸）的分辨率和6或20厘米（〜5英寸）的分辨率呈现连续图。无线电连续谱图显示，H n区域由浸没在〜6′（或21 pc）半径的漫射中的亮组分组成。明亮的组件具有紧凑的（0.7 pc）核心，周围有扩展的（3.4 pc）光晕。根据Wood＆Church-well（1989）的研究，紧凑型芯具有超紧凑型（0.04 pc）子组件。扩散发射的均方根电子密度为7 cm〜（-3），从一个结构到下一个小规模结构，其电子密度大约以10倍增加。观测到的无线电连续通量，其中一半是由漫射贡献的，因此需要O5 ZAMS的电离星。如果我们考虑Hn区域内的尘埃直接吸收电离的恒星光子，那么仅光亮成分就需要一个O5激发星。漫射连续谱发射的亮度沿其西边界急剧减小，并在其他方向逐渐减小。 VLA H I 21 cm线图显示，有H I云与陡峭的西部边界接触。 〜（13）CO线的观察结果表明，有一个与H n区相关的巨大分子云。无线电连续谱发射的明亮部分与分子云的密集核心相吻合。因此，G5.48 -0.24似乎是一个H II区域-分子云复合体，最近形成了大质量恒星。动态年龄（例如4 x 10〜3-2 x 10〜6年）的无线电连续体结构可能表明，连续的恒星形成正在进行，或者G5.48-0.24是水泡型H II区。

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