We carried out observations toward the giant molecular cloud W 37 with the J = 1 - 0 transitions of 12CO, 13CO and C180 using the 13.7 m single-dish telescope at the Delingha station of Purple Mountain Observatory. Based on these CO lines, we calculated the column densities and cloud masses for molecular clouds with radial velocities around ＋20 km s-1. The gas mass of W 37, calculated from 13CO emission, is 1.7 × 10^5 M, above the criterion to be considered a giant molecular cloud. The dense ridge of W 37 is a dense filament, which is supercritical in terms of linear mass ratio. Dense clumps found by C180 emission are aligned along the dense ridge at regular intervals of about 2.8 pc, similar to the clump separation caused by large-scale ＇sausage instability＇. We confirm the identification of the giant molecular filament （GMF） G 18.0-16.8 and find a new giant filament, G 16.5-15.8, located ~ 0.7° to the west of G 18.0-16.8. Both GMFs are not gravitationally bound, as indicated by their low linear mass ratio （- 80 M pc-l）. We compared the gas temperature map with the dust temperature map from Herschel images, and found similar structures. The spatial distributions of class I objects and the dense clumps are reminiscent of triggered star formation occurring in the northwestern part of W 37, which is close to NGC 6611.
Xiao-Liang ZhanZhi-Bo JiangZhi-Wei ChenMiao-Miao ZhangChao Song
We present a study of the Galactic bubble N4 using the 13.7 m millimeterwave telescope, which is managed by Purple Mountain Observatory at Qinghai Station. N4 is one of the science demonstration regions where simultaneous observations of ^12CO （J = 1 - 0）, ^13CO （J = 1 - 0） and C^18O （J = 1 - 0） line emission towards N4 were carried out under the project Milky Way Imaging Scroll Painting （MWISP）. We analyze the spectral profile and the distribution of the molecular gas. Morphologically, the CO emissions correlate well with Spitzer IRAC 8.0 p-m emission. The channel map and velocity-position diagram show that N4 is more likely to be an inclined expanding ring rather than a spherical bubble. We calculated the physical parameters of N4 including mass, size, column density and optical depth. Some massive star candidates were discovered in the region of N4 using the （J, J-H） colormagnitude diagram. We found a candidate for the energy source driving the expansion of N4, a massive star with a mass of -15 M⊙ and an age of - 1Myr. There is the signature of infall motion in N4, which can be a good candidate for the infall area. Combining millimeter and infrared data, we suggest that triggered star formation can exist in N4.
We report on a 95 GHz（80-71A＋） methanol（CH3OH） emission survey with the Purple Mountain Observatory Delingha 13.7 m telescope. Eight supernova remnants（SNRs） with angular size〈10′ were observed, but emission was only detected in three SNRs near the Galactic center（Sgr A East,G 0.1–0.1 and G 359.92–0.09）. CH3OH emission mainly surrounds the SNRs and can be decomposed into nine spatial peaks with the velocity range of eight peaks being（-30, 70） km s-1, and the other is（70, 120） km s-1. They are probably excited by interaction with these SNRs and adjacent molecular gas in the central molecular zone（CMZ）, although star formation may play an important role in exciting CH3OH emission in some regions of CMZ. We infer that tidal action is unlikely to be an excitation source for CH3OH emission.
