A statistical study of star formation by an extensive survey of molecular clouds

了解恒星是如何在星际空间形成的是现代天文学最重要的课题之一。对恒星形成过程的理解已经做出了相当大的努力。然而，到目前为止，大多数探测到的年轻恒星在光学上是可见的，或者具有很高的远红外光度。这表明，我们目前对恒星形成的看法可能严重偏向恒星形成的后期阶段，从而倾向于大质量恒星的形成。我们应该有一个公正的恒星形成区域样本，以便正确理解恒星形成，特别是在它被分子云严重遮挡的最早阶段。为了获得恒星形成区的无偏分子数据，名古屋小组一直在用两个4M射电望远镜测量太阳1-2Kpc范围内的分子气体。这项调查覆盖了几个100平方度的区域，是J=1-0 CO，^&lt；13；CO和…中扩展最广泛的完整样本之一在3 mm处有更多的C^&lt；18&gt；O光谱。其结果是在J=1-0 C^&lt；18&gt；O和J=2-1 CS谱中发现了与冷IRAS源有关的60个分子外流和大量致密的云核。在本研究中，根据名古屋望远镜的观测数据，我们得到了以下四个结果：1.发现了5个分子外流，其中包括在南方天空中的1个；2.详细研究了毫米波与远红外辐射的强度相关性；3.研究了密集核中速度场的关联长度；4.研究了暗云复合体周围原子氢的大尺度分布。此外，利用澳大利亚和智利的仪器，我们向在不久的将来在南方天空进行广泛的CO调查迈出了重要的一步。所发现的分子外流位于HII区IC5146附近的暗云团中，以及南方天空中HH132附近的暗云团中。特别是，用名古屋4米望远镜和马萨诸塞大学的14米望远镜首次以如此广泛的方式在CO、13&gt；CO和C^&lt；18&gt；O三个光谱中观察到了IC5146区域。这一区域将提供另一个很好的例子，说明在类似L1641云的致密云复合体中形成活跃恒星。较少

It is one of the most important subjects of modern astronomy to understand how stars are formed in interstellar space. Considerable efforts have been made toward the understanding of star formation processes. However, most young stars detected so far are optically visible or have high far infrared luminosities. This suggests that the view on star formation we have at present might be significantly biased toward the later stage of star formation and thus toward the massive star formation. We should have an unbiased sample of star formation regions in order to correctly understand star formation, particularly in it earliest stage heavily obscured in molecular clouds. In order to obtain unbiased molecular data of star formation regions, the Nagoya group has been surveying the molecular gas within 1-2 kpc of the sun by using the two 4m radio telescopes. This survey covers an area of a few 100 square degrees and is one of the most extended fully samples arc min in the J=1-0 CO, ^<13>CO and … More C^<18>O spectra at 3 mm. The results are discovery of 60 molecular outflows associated with cold IRAS sources, and numerous dense cloud cores in the J=1-0 C^<18>O and J=2-1 CS spectra. This certainly demonstrates that there are a number of star formation regions veiled from previous studies.In the present research, on the basis of the observational data with the Nagoya telescopes, we obtained following four results ; 1. discovery of five molecular outflows including one in the southern sky, 2. a detailed study of correlation in intensity between millimeter wave ^<13>CO and far infrared radiation, 3. a study of the correlation length of the velocity field in a dense core, and 4. a study of the large scale distribution of atomic hydrogen around dark cloud complexes. In addition these, we have marked an important step toward an extensive CO survey in the southern sky in the near future by using the instruments in Australia and Chile.The molecular outflows discovered are located in a dark cloud complex near an HII region IC5146, and near HH132 in the southern sky. Particularly, the IC5146 region was observed for the first time to such an extensive manner in three spectra, CO, ^<13>CO, and C^<18>O, with the Nagoya 4m telescope and with the 14m telescope at University of Massachusetts. This region will provide another good example of active star formation within a dense cloud complex similar to the L1641 cloud. Less