大质量分子云核和恒星形成活动

用国家台紫金山天文台13.7米望远镜的三谱线系统对23个有线翼特征的大质量恒星形成区进行了观测.获得了12个云核,发现其中5个具有外向流,2个有系统的速度变化,1个可能有塌缩,这些核的质量分布在9.4*10e2到2.2*10e5个太阳质量,氢分子密度从每立方厘米3.4*10e2到1.2*10e4.外向流的质量大于3.5个太阳质量,动能高于9*10e37焦耳,比低质量年轻星体附近的外向流大很多,每个核往往包含着几十个2mass源,其色指数和亮度各不相同,但最红的那个总是在IRAS源的误差椭圆内,可能就是IRAS源的对应体.

Massive molecular cloud cores and activities of star formation

We have mapped 23 sources in the $J$=1--0 lines of ¹²CO, ¹³CO and C¹⁸O with the 13.7-m telescope at Qinghai station of Purple Mountain Observatory.The samples were chosen from the massive star formation regions whose single point lines have the broad-wing profile. The mapping shows that 12 clouds have cores and 5 outflows were identified with the ¹²CO CO $J$=1--0 lines. Among the 12 cores, systematic velocity shifts were found in 2 cores, and blue asymmetric double-peak profile of ¹²CO line was found in IRAS 19529+2704, indicating that it may be an infall candidate. Physical parameters of the cores and outflows were derived from the local thermodynamic equilibrium assumption.The masses range from $\sim 9.4\times 10²M_{ \odot }$ to $\sim 2.2\times 10⁵M_{ \odot }$. The hydrogen molecule densities range from $\sim 3.4\times 10²{\rm cm}^-3 to $\sim 1.2\times 10⁴{\rm cm}^-3. The molecular outflows have masses larger than 3.5$M_{ \odot }$, and kinetic energies greater than 0.9$\times 10³⁸J. The outflows have significantly greater masses and kinetic energies than those from low-mass young stellar objects (YSOs). For the cores, 2MASS data are available, dozens of 2MASS sources with different colour indices and brightness are often found around IRAS source, among which the reddest 2MASS source is always within the IRAS error ellipse thus probably corresponds to the IRAS source.