Large-scale CO (J=1-0) Observations toward the M120.1+3.0 Molecular Cloud: A Filament with a Chain of Starburst Clusters

We present large-scale (2 degrees x 2 degrees) observations toward the molecular cloud M120.1+3.0, using (CO)-C-12, (CO)-C-13 and (CO)-O-18 (J= 1- 0) data from the Purple Mountain Observatory 13.7m millimeter telescope. The distance of the cloud is measured to be similar to 1.1 kpc. Using the (CO)-C-13 data, we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud, which together show a "hub-filament" structure. Filaments F1 and F2 are thermally supercritical. Furthermore, F1 displays clear localized systematic motions in the (CO)-C-13 position-velocity diagram, which could be explained by accretion along the filament. The mean estimated accretion rate is similar to 132M(circle dot) Myr(-1). Approximately 150 (CO)-C-13 clumps are identified in the cloud, of which 39 are gravitationally bound. Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2. Based on the complementary infrared and optical data, we identify similar to 186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1. The calculated star formation rate (SFR) surface densities (Sigma(SFR)) in the clusters range from 1.4 to 2.5 M-circle dot Myr(-1) pc(-2), with a mean value of similar to 2.0M(circle dot) Myr(-1) pc(-2). We therefore regard them as mini-starburst cluster candidates. The comparison between Sigma(SFR) and column density N-gas along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud. Along the main filament F1, five bipolar outflows are also found. All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.