Cluster-forming site AFGL 5157: colliding filamentary clouds and star formation

TL;DR

This study uses multi-wavelength observations to analyze star formation in AFGL 5157, revealing filamentary cloud collisions likely triggering massive star formation and embedded clusters within the region.

Contribution

It provides new evidence linking filamentary cloud collisions to massive star formation in AFGL 5157 using detailed multi-wavelength data.

Findings

Filamentary structures and embedded clusters are identified in AFGL 5157.

Collision of two filamentary molecular clouds likely triggers massive star formation.

Embedded clusters are distributed around an infrared shell with signs of ongoing star formation.

Abstract

We observationally investigate star formation (SF) process occurring in AFGL 5157 (area ~13.5 pc X 13.5 pc) using a multi-wavelength approach. Embedded filaments are seen in the {\it Herschel} column density map, and one of them is identified as an elongated filamentary feature (FF) (length ~8.3 pc; mass ~1170 Msun). Five Herschel clumps (Mclump ~45-300 Msun) are traced in the central part of FF, where an extended temperature structure (Td ~13.5-26.5 K) is observed. In the direction of the central part of FF, the warmer region at Td ~20-26.5 K spatially coincides with a mid-infrared (MIR) shell surrounding a previously known evolved infrared cluster. Diffuse H-alpha emission is traced inside the infrared shell, suggesting the presence of massive stars in the evolved cluster. Based on the surface density analysis of young stellar objects (YSOs), embedded clusters of YSOs are traced toward the central part of FF, and are distributed around the infrared shell. Previously detected H2O masers, H2 knots, massive protostar candidates, and HII region are also seen toward the embedded clusters. Using the 12CO and 13CO line data, the central part of FF is observed at the overlapping zones of two filamentary molecular clouds (length ~12.5 pc) around -20 and -17 km/s, which are also connected in velocity. Our observational results suggest that the formation of massive stars appears to be triggered by a collision of two filamentary molecular clouds, which might have also influenced the birth of YSOs in AFGL 5157.