A New Cloud–Cloud Collision Source N68 toward the G35 Molecular Cloud Complex

Bubble N68 in the G35 complex shows clear cloud–cloud collision (CCC) signatures. Its semiring-like morphology harbors many significant massive star formation tracers: 6 H ii regions, 4 6.7 GHz masers, 5 Midcourse Space Experiment sources, 9 radio peaks, and nearly 10 O/B-type stars. We also identified 163 young stellar objects (45 Class I, 5 Flat, 113 Class II), indicating active star formation toward N68. Our molecular study with CO reveals two distinct molecular clouds (N68a: 47–56 km s −1 ; N68b: 56–64 km s −1 ), with broad bridge features and complementary distributions at their borders, indicating an ongoing CCC. Star formation in N68 is collectively driven by collect-and-collapse (CC), radiation-driven implosion, and CCC mechanisms. However, compared with the CC and radiation-driven implosion mechanisms, the CCC mechanism does not enhance the star formation efficiency; instead, it tends to trigger the formation of massive stars. N68, along with bubbles N65 and N61, constructs a ∼100 pc scale CCC system in the G35 complex.