* Astronomy

Title: Discovery of Large-Scale Gravitational Infall in a Possible Massive Protostellar Cluster
Authors: Peter J. Barnes, Yoshinori Yonekura, Stuart D. Ryder, Andrew M. Hopkins, Yosuke Miyamoto, Naoko Furukawa, Yasuo Fukui
(Version v2)

We report Mopra (ATNF), Anglo-Australian Telescope, and Atacama Submillimeter Telescope Experiment observations of a molecular core in Carina, BY72 = G286.21+0.17, which give evidence of large-scale gravitational infall in the dense gas. From the millimetre and far-infrared data, the core has mass ~ 5,000 Msun, luminosity ~ 2-3 x 10^4 Lsun, diameter ~ 0.9 pc, and mass infall rate ~ 2.4 x 10^-2 Msun yr-1. If confirmed, this rate for gravitational infall in a molecular core may be the highest yet seen. The near-infrared K-band imaging shows an adjacent compact HII region and IR cluster surrounded by a shell-like photodissociation region showing H2 emission. At the molecular infall peak, the K imaging also reveals a deeply embedded group of stars with associated H2 emission. The combination of these features is very unusual and we suggest they indicate the ongoing formation of a massive star cluster. We discuss the implications of these data for competing theories of massive star formation.

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