Tsan-Ming Wang(Graduate Institute of Astronomy, National Central University); Chorng-Yuan Hwang(Graduate Institute of Astronomy, National Central University)
We investigate the influence of the random velocity of molecular gas on the star forming activities in molecular clouds. It is known that physical states of a molecular cloud, such as temperature and density, will influence the star forming activities in the cloud. Besides, it is believed that local and turbulent motions of the molecules in the cloud might provide a significant amount of pressure against gravitational collapse and might thus prevent or reduce star formation in the cloud. However, the influence of the gas motions on the star formation activities is still poorly understood. To probe the effects of the gas motion on the star formation, we use high spatial-resolution Atacama Large Millimeter/submillimeter Array (ALMA) data to obtain 12CO(J=1-0) flux and velocity dispersion, besides combine with 3.6 and 8 micron mid-infrared datas from Spitzer Space Telescope, trying to study the relation between star formation rates(SFRs), molecular gas mass and velocity dispersions on different regions of nearby galaxies. Finally we establish an modified Schmidt law with an additional parameter velocity dispersion, it tells us the higher the turbulence in a molecular cloud, the stronger it will prevent also reduce star formation in a cloud. In this paper, we present our current results and discuss their implication.