STAR FORMATION AROUND MID-INFRARED BUBBLE N37: EVIDENCE OF CLOUD–CLOUD COLLISION

Abstract

ABSTRACT We have performed a multi-wavelength analysis of a mid-infrared (MIR) bubble N37 and its surrounding environment. The selected 15′ × 15′ area around the bubble contains two molecular clouds (N37 cloud; 37–43 km s−1, and C25.29+0.31; 43–48 km s−1) along the line of sight. A total of seven OB stars are identified toward the bubble N37 using photometric criteria, and two of them are spectroscopically confirmed as O9V and B0V stars. The spectro-photometric distances of these two sources confirm their physical association with the bubble. The O9V star appears to be the primary ionizing source of the region, which is also in agreement with the desired Lyman continuum flux analysis estimated from the 20 cm data. The presence of the expanding H ii region is revealed in the N37 cloud, which could be responsible for the MIR bubble. Using the 13CO line data and photometric data, several cold molecular condensations as well as clusters of young stellar objects (YSOs) are identified in the N37 cloud, revealing ongoing star formation (SF) activities. However, the analysis of ages of YSOs and the dynamical age of the H ii region do not support the origin of SF due to the influence of OB stars. The position–velocity analysis of 13CO data reveals that two molecular clouds are interconnected by a bridge-like structure, favoring the onset of a cloud–cloud collision process. The SF activities (i.e., the formation of YSO clusters and OB stars) in the N37 cloud are possibly influenced by the cloud–cloud collision.