Observational study of galaxy evolution with large-scale surveys of molecular clouds along the Galactic plane

我们开发了基于波导的正交模换能器（OMT）的双偏振观测安装在1.85米毫米亚毫米望远镜，提高了2倍的观测效率。 利用该系统，我们成功地覆盖了银河平面上沿着1250平方度的区域，包括猎户座、金牛座、英仙座、天鹅座、加州星云、巨蛇座等各种星星形成区域。 通过对猎户座分子云的观测研究，发现13 CO（2-1）线是精确反演分子云密度和温度的重要探针。

We developed waveguide-based Orthomode Transducers (OMT) for dual-polarization observations to be installed on the 1.85m mm-submm telescope, which improved the observation efficiency by a factor of 2. With this system, we have succeeded in covering 1250 square degrees along the Galactic plane including various star forming regions of Orion, Taurus, Perseus, Cygnus, California nebula, Serpens, and so on. The development is summarized in Onishi et al. (2013). We found that 13CO(2-1) line is an important probe to precisely derive the density and temperature of molecular clouds through an observational study of molecular clouds toward Orion molecular clouds.