The Stellar Snake I Whole Structure and Properties
报告人:
田海俊,三峡大学教授,湖北省天文学会副理事长,三峡学者,德国马克思普朗克天文所(MPIA)访问学者。近年研究兴趣主要包括:大型自行星表构建、宽距双星、银河系结构与演化等。主持国家自然基金三项,参与国家重点基金一项,先后获得湖北省杰出青年基金、中欧人才、学校“青年拔尖人才”、三峡学者(第一层次)等人才项目的支持,发表学术论文30余篇,其中,太阳本动速度、GPS1自行星表、宽距双星等三项研究成果分别被天文和物理领域最重要的年鉴性评论期刊《天文学和天体物理学年度评论》和《核与粒子科学年度评论》引述或亮点评述。摘要:
To complement our previous discovery of the young snake-like structure (Tian, 2020, ApJ, 904, 196) in the solar neighborhood and reveal the structure’s full extent, we build two samples of stars within the Snake and its surrounding territory from Gaia EDR3. With the friends-of-friends algorithm, we identify 2694 and 9615 Snake member candidates from the two samples. Thirteen open clusters are embedded in these member candidates. By combining the spectroscopic data from multiple surveys, we investigate the comprehensive properties of the candidates and find that they actually belong to one sizable structure, since most of the components are well bridged in their spatial distributions, and follow a single stellar population with an age of 30−40 Myr and with solar metallicity. This sizable structure should be a hierarchically primordial structure, and probably formed from a filamentary giant molecular cloud with different formation history in the local regions. The whole structure is expanding. To further analyze the dynamics of the Snake, we divide the structure into five groups according to their tangential kinematics. We find that the groups are expanding at a coherent rate (κ_X ~ 3.0 × 10^{−2} km/s/pc) along the length of the structure (X direction). The corresponding expansion age (τ~33 Myr) is highly consistent with the age of the Snake. With over ten thousand member stars, the Snake is an ideal laboratory to study nearby coeval stellar formation, stellar physics, and environmental evolution over a large spatial extent.