13CO (J = 1 ? 0) emission of massive star forming region including 15 ultracompact and 4 compact HII regions in Galactic plane was mapped with the 13.7 m millimeter wave telescope of Purple Mountain Observatory. The present observations provide the first complete structure of the clouds in 13CO with a higher spatial resolution and a wide-field coverage of 28′ x 45′. Combined with the images of far-infrared emission and dust color temperature obtained from ISSA, various possible dynarnical connections between the compact HII regions and associated clouds were found. We presente some reasons to explain the formation of new dense cold core and molecular emission cavity in the massive star formation and early evolution. The luminosities of excitation stars for all HI1 regions and the main parameters of associated clouds are also derived. The results show that the newborn stars’ luminosities are correlated with the13CO column densities, masses (in 55″beam) and 13CO velocity widths obviously.
We report the results of CO(1-0) (J=l-0) observations for 20 selected planetary nebulae (PNe), using the 13.7 m radio telescope of Purple Mountain Observatory at the Qinghai Station. Due to weak CO(1-0) emission, long integrated time observations have been carried out for most of sampled PNe. Among these PNe, nine are first detections in CO(1-0) named NGC 6445, Ml-59, M4-9, M2-51, M4-18, He2-459, Sh2-71, K3-31, M2-52, and one is the first possible detection named V-Vl-8, a probably misclassified PN. NGC 6445, Ml-59, M4-9 and M2-51 have been detected in CO(2-1)(J=2-1). Although having been observed in previous CO surveys, Sh2-71 and M4-18 were not detected in CO; M2-52, K3-31, He2-459 are the first detected PNe in CO emission and V-Vl-8 is given with a first completed spectrum detected in CO(1-0). Comparing these data with other previous observational ones, we discuss the relationships between CO(1-0) emission and evolution of PNe: While the nebular radii increase, the CO(l-0) line integrated intensities multiplied by distances have a decreasing trend. Also the masses of molecular envelopes (from 0.001 to 1 M⊙) for PNe are decreased with increasing nebular radii. All the results mean the CO(1-0) emission decreases dramatically with the nebular evolution. The detectability of CO restricted by different PNe which have different dust properties and different evolutionary stages is also analyzed.
It is recognized that the interstellar methanol 107 GHz and OH 4 765 GHz masers toward Class Ⅱ sources are associated with each other and coexist toward ultracompact HⅡ regions. A new excitation mechanism is suggested. It can explain the formation of methanol 107 GHz masers. And it is argued that this mechanism is associated with astronomical conditions.
The features of the interstellar classⅡ methanol source reg io ns are grasped. A new pumping mechanism is argued. It can explain the formation of a series of J 0→J -1 E methanol masers and the increase of the maser intensity with J, while the 2 1→3 0A-+ methanol masers are regard ed as driving coherent microwave field.
