A Search for Low-Frequency Recombination Lines in the Southern Galaxy

该奖项将支持对我们银河系平面南部低频谱线的调查。这些谱线是由电离的碳原子重新组合成主量子数在272和768之间的高量子态而产生的；对应的线路频率为325mhz ~ 14.5 MHz。产生这些线的原子非常大，直径可达50微米，非常脆弱。这样的原子只能在凉爽的星际云的温和条件下存在，而且它们对环境极其敏感。因此，它们可以很好地诊断低温星际云中的温度、压力和电离水平。以前所有的观测都是用北半球的望远镜进行的。这次调查将使用澳大利亚的帕克斯望远镜覆盖银河平面的南部和麦哲伦星云，以发现更多的线发射区域。

This award will support a survey of low frequency spectral lines from the southern portion of the plane of our Galaxy. The lines are produced by the recombination of ionized carbon atoms into very high quantum states with principal quantum numbers between 272 and 768; the corresponding frequencies of the lines are 325 MHz to 14.5 MHz. The atoms producing these lines are extremely large and fragile with diameters up to 50 microns. Such atoms can exist only under the benign conditions found in cool interstellar clouds, and they are extremely sensitive to their environment. For this reason they are excellent diagnostics of temperature, pressure, and ionization levels in cool interstellar clouds. All previous observations have been made with northern hemisphere telescopes. This survey will cover the southern portion of the galactic plane and the Magellanic Clouds using the Parkes telescope in Australia in order to discover more line emitting regions.