Star formation and ionized regions throughout the inner Galactic plane

Abstract

We present a comprehensive statistical analysis of star-forming objects located in the vicinity of 1360 bubble structures throughout the inner Galactic Plane. The compilation of ∼70 000 star-forming sources, detected in both HI-GAL and GLIMPSE surveys, provided a broad overview of the different evolutionary stages of star-formation in bubbles, from prestellar objects to more evolved Young Stellar Objects (YSOs). Surface density maps reveal a clear evolutionary gradient and ∼80% more sources per unit area in the direction of the bubbles compared with the surrounding outer fields. We derived dynamic ages and clump formation efficiencies for a subsample of 182 bubbles and found that younger bubbles are typically more efficient at forming clumps. Approximately 23% of the HI-GAL clumps are located in the direction of a bubble, with 15% for prestellar clumps and 41% for protostellar clumps. We argue that the high fraction of protostellar clumps may be due to the acceleration of the star-formation process caused by the feedback of the bubbles.