Xi S, Qin S, Deng L, Yang J
Purple Mountain Observatory, Chinese Academy of Sciences, 210008 Nanjing.
Guang Pu Xue Yu Guang Pu Fen Xi. 2001 Aug;21(4):456-8.
Stars are the basic building blocks of our universe, therefore it is one of the most important research topics in astrophysics to understand the origin and the early evolution of these objects. The current picture is that stars are formed during the collapse of a large enough self-gravitating interstellar molecular cloud. The early collapse gives birth to a fetus of a star, which is surrounded by a rotating accretion disk. The proto-star accretes interstellar matter through the disk which in turn transfer the accumulated matter to the central proto-star, then the star gets weight during the process. Observation shows that gorgeous ejection of matter always come along with the accretion process. In the presence of disks, these outflows usually escape from the system along the axis of the disk, forming so called bipolar outflows. Typical tracers of these activities are rich molecules such as CO, SiC2, C3H, C3H2 etc. Observationally, such typical molecular outflows can be detected using Doppler effect by spectroscopic measurements. Using the 13.7 m radio telescope in Delingha station of Purple Mountain Observatory, we performed a survey for 12 low temperature IRAS objects, some of the sources show high velocity properties. Detailed analysis of the Doppler profiles of IRS34 is presented. Star forming activities are clearly seen in this field.
恒星是宇宙的基本构成要素,因此了解这些天体的起源和早期演化是天体物理学中最重要的研究课题之一。目前的情况是,恒星在足够大的自引力星际分子云坍缩过程中形成。早期坍缩产生了恒星的雏形,它被一个旋转的吸积盘所包围。原恒星通过吸积盘吸积星际物质,吸积盘再将积累的物质转移到中央原恒星,于是恒星在这个过程中逐渐增重。观测表明,物质的剧烈抛射总是伴随着吸积过程。在存在吸积盘的情况下,这些外流通常沿着吸积盘的轴线逃离系统,形成所谓的双极外流。这些活动的典型示踪剂是诸如一氧化碳、碳化硅、丙炔、丙二烯等丰富的分子。在观测上,这种典型的分子外流可以通过光谱测量利用多普勒效应来检测。利用紫金山天文台德令哈站的13.7米射电望远镜,我们对12个低温红外天文卫星源天体进行了巡天观测,其中一些源显示出高速特性,并给出了对IRS34多普勒轮廓的详细分析。在这个区域可以清楚地看到恒星形成活动。