Science News：

　　报告人：刘铁

　　Journal Club Public Talk:

　　报告人：赵起

　　报告题目：Evidence for delayed massive star formation in the M17 proto-OB association

　　报告摘要：Through analysis of archival images and photometry from the Spitzer GLIMPSE and MIPSGAL surveys combined with Two Micron All Sky Survey and MSX data, we have identified 488 candidate young stellar objects (YSOs) in the giant molecular cloud M17 SWex, which extends 50 pc southwest from the prominent Galactic Hii region M17. Our sample includes >200 YSOs with masses >3M⊙ that will become Btype stars on the main sequence. Extrapolating over the stellar initial mass function (IMF), we find that M17 SWex contains >1.3×104 young stars, representing a proto-OB association. The YSO mass function is significantly steeper than the Salpeter IMF, and early O stars are conspicuously absent from M17 SWex. Assuming M17 SWex will form an OB association with a Salpeter IMF, these results reveal the combined effects of (1) more rapid circumstellar disk evolution in more massive YSOs and (2) delayed onset of massive star formation.

　　参考文献：http://adsabs.harvard.edu/abs/2010ApJ...714L.285P

　　时间：2016年12月13日12:15－1:45pm

　　地点：紫台619会议室