暗分子云核L183的射电观测和尘气相互作用

RADIO OBSERVATIONS OF DARK MOLECULAR CLOUD CORE L183 AND GAS DEPLETION ON GRAINS

利用青海德令哈观测站 13.7m射电望远镜对暗分子云核L183作成图观测 ,选用的谱线为C18O(J=1 0 ) .与Swade利用NH3(1,1)谱线所作的等积分强度图比较 ,发现NH3图中的 2个极值位置位于C18O密度分布的低密度谷区 .由于NH3的辐射与尘埃的红外辐射分布相关 ,所以C18O分子密度的减少是因为尘埃吸附 .

A 13.7 m radio telescope,operating in millimeter waves and placed in Dalingha, Qinghai province, was employed to map the dark molecular cloud core of Lynds 183 with the molecular emission line of C 18 O(J=1 0). A typical C 18 O(J=1 0) line profile and the contour map of integrated intensity (∫T * Ad v) have been shown. In comparison with the NH 3 (1,1) contour map, done by Swade using FCRAO ( Five College Radio Astronomy Observatory) telescope for the same core, the positions of the two peaks in the NH 3 (1,1) integrated intensity map are corresponding to a relatively low density trough of gas in our C 18 O(J=1 0) map. It leads to the suggestion that C 18 O molecules should be depleted on grains populated in the core, because the peak of NH 3 emission in its integrated intensity map evidently coincides with the dust peak in 200 μm continuum emission according to some studies. It is, therefore, unable to see the dark cloud cores on the verge of collapse in the early stage of star formation to use C 18 O molecular emission lines only.