Star Formation Activity in the Molecular Cloud G35.20-0.74: Onset of Cloud-Cloud Collision

Abstract

To probe star formation (SF) processes, we present results of an analysis of the molecular cloud G35.20-0.74 (hereafter MCG35.2) using multi-frequency observations. The MCG35.2 is depicted in a velocity range of 30-40 km s^-1. An almost horseshoe-like structure embedded within the MCG35.2 is evident in the infrared and millimeter images and harbors the previously known sites, ultra-compact/hyper-compact G35.20-0.74N H II region, Ap2-1, and Mercer 14 at its base. The site, Ap2-1, is found to be excited by a radio spectral type of B0.5V star where the distribution of 20 cm and Hα emission is surrounded by the extended molecular hydrogen emission. Using the Herschel 160-500 μm and photometric 1-24 μm data analysis, several embedded clumps and clusters of young stellar objects (YSOs) are investigated within the MCG35.2, revealing the SF activities. A majority of the YSOs clusters and massive clumps (500-4250 {M}_⊙ ) are seen toward the horseshoe-like structure. The position-velocity analysis of ¹³CO emission shows a blueshifted peak (at 33 km s^-1) and a redshifted peak (at 37 km s^-1) interconnected by lower intensity intermediate velocity emission, tracing a broad bridge feature. The presence of such a broad bridge feature suggests the onset of a collision between molecular components in the MCG35.2. A noticeable change in the H-band starlight mean polarization angles has also been observed in the MCG35.2, probably tracing the interaction between molecular components. Taken together, it seems that the cloud-cloud collision process has influenced the birth of massive stars and YSOs clusters in the MCG35.2.