The Dynamic Research Of The W3/4/5 Cloud Complex

Stars form from molecular clouds.Protostellar outflows are important process of early star formation.On one hand,outflows entrain a part of angular momentum from a younger star and its disk which can promote star forming;on the other hand,outflows inject momentum and kinetic energy which can support the turbulence of the cloud or even disrupt the entire cloud.Outflows and their parent cloud intermingle with each other.Therefore,we choose the outflow activity to study the dynamics of the cloud.The MWISP(Milky Way Imaging Scroll Painting project)create conditions for us to conduct 12CO outflow survey and a study on feedback of CO outflow candidates on their parent clouds over a large region.We selected a pilot region of～110 deg2 toward the W3/4/5 complex and its surroundings.In chapter 2,we conducted a large-scale 12CO outflow survey over this region.We detected 459 outflow candidates in all,of which 284 were located in the Perseus arm(include W3/4/5 complex),162 in the Local arm,5 in the Outer arm,and 8 in two inter-arm regions.This suggested that star formation was mainly concentrated in the Galactic spiral arms.We presented the spatial distribution of all outflow candidates.The results indicated that the region which showed the most active star formation was the Perseus arm.One of the great regions to research massive star formation in a triggered environ-ment is the W3/4/5 cloud complex.The most important and most active studied region is in the eastern high-density W3 complex that neighbors the W4 complex.The Local arm contains candidates to study the impact on star formation imposed by massive or intermediate-mass stars,and the most important candidates are two shell-like structures which are in relatively isolated systems.In the two interarm regions and the Outer arm,most outflow candidates are located in filamentary structures.Few studies have focused on protostellar outflow feedback on the scale larger than several parsecs.In chapter 3,we conducted a study on feedback of CO outflow candi-dates on their parent clouds based on the outflow survey in chapter 2.We found 26513CO clouds where the radii were ranged from～0.1 to～28.2 pc.136 clouds were located in the Perseus arm,124 in the Local arm and 5 in the interarm 1.We evaluated the feedback of outflow candidates in two aspects:the turbulent support and disruptive effect of outflow candidates.The first one was evaluated by the ratios of the kinetic energy and momentum in outflow candidates to those in cloud turbulence;and the sec-ond one was calculated by the ratio of the kinetic energy in outflow candidates to that in cloud gravitational binding and the ratio of escape mass(the mass that could potentially be dispersed by the outflows)to cloud mass.The four ratios as functions of cloud radius can be fitted by power law profiles,and the indexes are negative.By comparing these fitted lines and ratios of unity,we found that ejecta of outflow activities were enough to maintain the turbulence on the scale of≤0.1-0.4 pc,and outflow activities could be expected to disperse the cloud material away from the parent cloud on the scale of≤0.2—0.3 pc.The four ratios start to flatten out when the radius is～6 pc,this indicate that the influence radius exceeds～6 pc.Outflow feedback can potentially sculpture the linewidth-size relation because the linewidth-size relation steepened when we deducted the momentum inj ected by outflow candidates.Outflow feedback may also shape cloud mass function.We conducted a 95 GHz(80-71 A＋)methanol(CH3OH)emission survey toward eight supernova remnants(SNRs,their angular size≤10’)by using the Purple Mountain Observatory Delingha 13.7 m telescope.We detected methanol emission only toward three SNRs near the Galactic center(Sgr A East,G 0.1-0.1 and G 359.92-0.09).