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

恒星是如何在星际空间中形成的是现代天文学的重要课题之一。人们为理解星星的形成过程做了大量的努力。然而，迄今为止发现的大多数年轻恒星都是光学可见的，或者具有很高的远红外光度。这表明，我们目前对星星形成的看法可能明显偏向于星星形成的后期，从而偏向于大质量星星的形成。为了正确理解星星的形成，特别是在分子云中被严重遮蔽的最早阶段，我们应该有一个无偏见的星星形成区样本。为了获得无偏差的星星形成区的分子数据，名古屋小组一直在利用两台4米射电望远镜对太阳1-2千秒差距内的分子气体进行观测。这次调查覆盖了几百平方度的面积，是J=1-0 CO，^<13>CO和 ...更多信息 结果<18>发现了60个与冷IRAS源有关的分子外流，在J=1-0 C^<18>O和J=2-1 CS谱中发现了大量致密云核。这无疑表明，在过去的研究中，有许多星星形成区被掩盖了。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.发现五个分子外流，包括一个在南天，2。详细研究了毫米波CO<13>与远红外辐射强度的相关性。致密核中速度场相关长度的研究;对暗云复合体周围原子氢的大尺度分布的研究。此外，我们还利用澳大利亚和智利的仪器在南天进行了大范围的CO观测，并在南天发现了位于HII区IC 5146附近的暗云复合体和HH 132附近的分子外流。特别是在名古屋4米望远镜和马萨诸塞州大学的14米望远镜上，首次在CO、^ CO和C^ O三个光谱中以如此广泛的方式观测到IC 5146区<13><18>。这个区域将提供另一个很好的例子，说明在类似于L1641云的致密云复合体中活跃的星星的形成。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