报告题目：How to Make Massive Stars

　　报 告 人：Qizhou Zhang （Harvard-Smithsonian Center for Astrophysics）　　

　　报告摘要：Massive stars dominate the appearance and the evolution of galaxies. Despite their prominence, their formation is not well understood. In the Milky Way, most young massive stars are found in parsec-scale molecular clumps. Their birth is linked to the collapse and fragmentation of massive molecular clumps and clustered star formation. It appears that massive star formation is about fighting against the odds every step in the way. The physical conditions (temperature and density) in a molecular clump limit the Jeans mass to about 1 Msun. This creates the first barrier for massive star formation since dense cores much larger than 1 Msun tend to further fragment into lower mass cores. Once protostars reach more than 8 Msun, the radiation pressure may halt the infall and prohibit stars from further mass growth. At a later stage when massive young stars reach 15-20 Msun, ionization may reverse mass inflow through HII region expansion. In this talk, I will review recent progress in massive star formation studies and discuss how nature overcomes these barriers to form massive giants in the stellar nursery.

　　时    间：2014年4月23日星期三 上午10:00

　　地    点：（北京西路2号）紫台大楼619会议室

欢迎大家积极参加！

　　                                    紫金山天文台学术委员会学术交流工作委员会