Unbiased surveys for dense cloud cores using multi-beam supercondutcing receiver

我们用两台4米毫米波望远镜进行了大规模的观测，获得了天鹅座、仙后座、蛇夫座、巨蛇座和金牛座等地的约30万条^CO（J = 1 - 0）发射光谱。<13>观测面积占全天面积的15%，是^CO观测范围最广的一次。我们识别了1,000多个^CO云，并分析了这些云的物理参数。<13><13>通过与IRAS点源的比较，分析了各星云的星星形成活动以及新生恒星特征与星云特征之间的关系。这是第一次基于如此均匀的光谱数据来分析云的特征。结果表明：（1）云的质量谱在100 - 10，000 M_（？）范围内，呈指数为-1.7的幂律分布。<of sun>(2)每个星云中最亮的星星的光度与星云的质量之间存在关系;即，通过对金牛座地区的详细观测，我们还发现了以下三点：（1）金牛座云的基本结构是球状的;（2）在柱密度最高的地方，星星已经形成;（3）在形成后不久，高密度分子气体消失。<13>我们通过对比^CO透明的C ^O的观测，详细研究了云的稠密区，发现上述关系式（2）和（3）比^CO更有意义，这些结果对于理解分子气体中星星的形成是有价值的知识。<18><13><13>

We have carried out a large-scale survey with two 4 meter millimeter-wave telescopes, and obtained about 300,000 spectra of ^<13>CO (J=1-0) emission toward the Cygnus, Cassiopeia, Ophiuchus, Serpens and Taurus regions. The observed area corresponds to 15% of the whole sky, which makes this survey the most extensive one among those made in ^<13>CO.We have identified more than 1,000 ^<13>CO clouds and analyzed the physical paramerers of these clouds. Comparing with the IRAS point sources, we have examined the star formation activity of each cloud and the relationship between the characteristics of newly-born stars and those of clouds. This is the first time to analyze characteristics of clouds based on such a uniform spectral data. As a result, following two points are found :(1) The mass spectrum of clouds is expressed as a power-law with the index-1.7 in the range 100-10,000 M_<<of sun>>.(2) There is a relationship between the luminosity of the most luminous star within each cloud and the mass of the cloud ; i.e., the maximum stellar luminosity increases with the cloud mass.We have also found the following three points through the detailed ^<13>CO observations toward Taurus region ; (1) the basic structure of the Taurus cloud is filamentary, (2) star formation has taken place where the column density reaches its highest and (3) soon after the formation occurs, high-density molecular gas disappears. We have studied the dense regions of clouds in detail by observations of C^<18>O,which is more transparent than ^<13>CO,and found that above relations (2) and (3) are more significant than in ^<13>CO.These results are valuable knowledge in order to understand the star formation within molecular gas.