Star formation around mid-infrared bubble N37: Evidence of cloud-cloud collision

Abstract

We have performed a multi-wavelength analysis of a mid-infrared (MIR) bubble N37 and its surrounding environment. The selected 15${}^{\prime }\times$15${}^{\prime }$ area around the bubble contains two molecular clouds (N37 cloud; V${}_{lsr}\sim$37-43 km s${}^{-1}$, and C25.29+0.31; V${}_{lsr}\sim$43-48 km s${}^{-1}$) along the line of sight. A total of seven OB stars are identified towards the bubble N37 using photometric criteria, and two of them are spectroscopically confirmed as O9V and B0V stars. Spectro-photometric distances of these two sources confirm their physical association with the bubble. The O9V star is appeared 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 HII region is revealed in the N37 cloud which could be responsible for the MIR bubble. Using the ${}^{13}$CO 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 HII region do not support the origin of SF due to the influence of OB stars. The position-velocity analysis of ${}^{13}$CO data reveals that two molecular clouds are inter-connected by a bridge-like structure, favoring the onset of a cloud-cloud collision process. The SF activities (i.e. the formation of YSOs clusters and OB stars) in the N37 cloud are possibly influenced by the cloud-cloud collision.

18 pages, 13 figures, 2 tables, Accepted for publication in the ApJ

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• Star Formation Activity in the molecular cloud G35.20$-$0.74: onset of cloud-cloud collision
• Unveiling molecular clouds toward bipolar HII region G8.14+0.23
• Infrared dust bubble CS51 and its interaction with the surrounding interstellar medium
• Ultracompact HII regions with extended emission: The case of G43.89-0.78 and its molecular environment
• A systematic study of Galactic infrared bubbles along the Galactic plane with AKARI and Herschel. II. Spatial distributions of dust components around the bubbles
• Gas dynamics in the star forming region G18.148$-$0.283: Is it a manifestation of two colliding molecular clouds?
• Ammonia mapping observations of the Galactic infrared bubble N49: Three NH${}_3$ clumps along the molecular filament
• TIFR Treasures for Astronomy from Ground to Space