A large-scale CO mapping of the central region of W 51

Abstract

We present a high-resolution (16″) 13CO (J = 1-0) map of the central region of W 51. We observed an area of about 15′.3 × 16′.7, which covers the entire region of G49.5-0.4, the brightest source in the W 51 region. Four discrete molecular clouds were identified toward G49.5-0.4, and evidence of cloud-cloud collisions was found. We speculate that a "pileup" of three molecular clouds resulted in a burst of massive star formation in G49.5-0.4.