Stellar feedback and triggered star formation in the prototypical bubble RCW 120

Radiative and mechanical feedback of massive stars regulates star formation galaxy evolution. Positive triggers the creation new by collecting dense shells gas, while negative disrupts shredding molecular clouds. Although key to understanding formation, their relative importance is unknown. Here, we report velocity-resolved observations from SOFIA (Stratospheric Observatory for Infrared Astronomy) legacy program FEEDBACK star-forming region RCW 120 in [CII] 1.9-THz fine-structure line, revealing a gas shell expanding at 15 km/s. Complementary APEX (Atacama Pathfinder Experiment) CO J=3-2 345-GHz exhibit ring structure fragmented into clumps that are actively forming stars. Our demonstrate triggered can occur on much shorter time scales than hitherto thought (<0.15 million years), suggesting positive operates short periods.