Observational Study of the Physical Properties of the Hierarchy Commonly Found in Star-Forming Molecular Clouds

点击翻译按钮获取中文摘要

We have made high-quality mapping observations toward the three typical star-forming clouds (Taurus, Orion, and Ophiuchus), in order to investigate the hierachical structure in molecular clouds and its influence on star formation. The Nobeyama 45 m telescope equipped with the 25-beam array receiver system (BEARS) makes it possible to homogeneously cover the spatial ranges from the overall extension (-1 pc) of the clouds down to small scales (-0.01 pc) comparable to cloud cores. Our main results are as follows.1. Development of a new data analysis system (BMAS) for BEARS observations.We have developped a new analysis system (BMAS) for large-scale and high-resolution mapping data with BEARS.We used the programming language, IDL on workstation platforms and BMAS has GUI which is user-friendly. Standard analysis tools in radio astronomy and statistical analysis tools including spectral analysis are built in BMAS.One can efficiently analyze huge data from BEARS with BMAS.2. Dominance of smaller clumps than cores in molecular clouds.We have found that fine structures (clumps) smaller than cores are dominant in molecular clouds by analyzing the BEARS high-quality mapping data with BMAS.The clumps are considered to play an important role in star formation within cloud cores. Furthermore, we found the following new results for individual clouds, In the Taurus cloud, we propose a new classification of protostars based on the spatial distribution of dense gas. In the Orion cloud, there exist fine filaments in the well-known large-scale filamentary structure. And in the Ophiuchus cloud, we revealed the early evolution of star-forming cores by comparing our mapping data with the infrared images taken by ISO.Our analysis is in progress.