Low-frequency carbon recombination lines in the central regions of the galaxy
Low-frequency carbon recombination lines in the central regions of the galaxy
复制标题
银河系中心区域的低频碳重组线
DOI：
10.1086/176471
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
K. Anantharamaiah
中科院分区：
文献类型：
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作者：
W. Erickson;D. McConnell;K. Anantharamaiah
我们已经使用帕克斯64米望远镜研究低频碳复合线从银河系平面的南部部分在一个频带4兆赫宽，中心在76.4兆赫。我们发现了一个非常大的谱线形成区，它在银河经度上从1 = 340°延伸到1 = 20°，大约40 °。这个地区的纬度宽几度。根据径向速度和谱线宽度随银河经度的变化，我们得到了到谱线形成区的运动学距离在0.5-4千秒差距的范围内。这将线形成区域放置在人马座和/或盾牌臂。我们还发现这些线在1 = 312处近似与盾臂相切。通过对C441α、C555β和C635γ谱线的观测，估计了谱线强度随主量子数的变化。这种变化似乎类似于观察到的英仙座臂在Cas A方向的吸收，并表明英仙座臂线形成区域的模型可能至少部分适用于射手座/盾牌座臂区域。这些谱线最可能的形成地点是星际介质中冷的中性H I浓度。我们还搜索了其他线的数据，特别是，我们没有发现氢复合线的痕迹。
We have used the Parkes 64 m telescope to study low-frequency carbon recombination lines from the southern portion of the Galactic plane in a frequency band 4 MHz wide centered at 76.4 MHz. We have found a very large line-forming region that extends for approximately 40 in Galactic longitude from 1 = 340° to l = 20°. The region is several degrees wide in latitude. From the variation of radial velocity and line width with Galactic longitude we obtain kinematic distances to the line-forming region in the range 0.5-4 kpc. This places the line-forming region in the Sagittarius and/or Scutum arms. We also find the lines approximately tangent to the Scutum arm at 1 = 312 . By observing the C441α, C555β, and C635γ lines, which all occur in the analyzed band, we estimate the variation of line strength with principal quantum number. This variation appears to be similar to that of the well-observed Perseus arm absorption in the direction of Cas A and suggests that a model for the Perseus arm line-forming region may be at least partially applicable to the Sagittarius/Scutum arm regions. The most likely sites for the formation of these lines are the cold neutral H I concentrations in the interstellar medium. We have also searched the data for other lines and, in particular, we find no trace of hydrogen recombination lines.