2017ApJ...838...49X

We present large-field (4.25 x 3.75 deg²) mapping observations toward the Galactic region centered at l=150^○,b=3○^ / . 5 in the J = 1-0 emission line of CO isotopologues (¹²CO, ¹³CO, and C¹⁸O), using the 13.7 m millimeter-wavelength telescope of the Purple Mountain Observatory. Based on the ¹³CO observations, we reveal a filamentary cloud in the Local Arm at a velocity range of -0.5 to 6.5 km s^–1. This molecular cloud contains 1 main filament and 11 sub-filaments, showing the so-called "ridge-nest" structure. The main filament and three sub-filaments are also detected in the C¹⁸O line. The velocity structures of most identified filaments display continuous distribution with slight velocity gradients. The measured median excitation temperature, line width, length, width, and linear mass of the filaments are ∼9.28 K, 0.85 km s^–1, 7.30 pc, 0.79 pc, and 17.92 M_☉ pc^–1, respectively, assuming a distance of 400 pc. We find that the four filaments detected in the C¹⁸O line are thermally supercritical, and two of them are in the virialized state, and thus tend to be gravitationally bound. We identify in total 146 ¹³CO clumps in the cloud, about 77% of the clumps are distributed along the filaments. About 56% of the virialized clumps are found to be associated with the supercritical filaments. Three young stellar object candidates are also identified in the supercritical filaments, based on the complementary infrared data. These results indicate that the supercritical filaments, especially the virialized filaments, may contain star-forming activities.