Prof. Yuefang Wu (Peking Univ.) visit our group and give colloquium speech

Feb 19, 2010

“Gravitational collapse in high-mass star formation region”

The high-mass star formation mechanisms remain unclear. By calculation, when a forming star reaches 8 Msun, its radiation pressure can halt spherical infall, preventing its further growth. Two major theoretical models on the further growth of such stars were suggested. One model suggested the mergence of low mass stellar objects, and the other suggested a process through accretion-disk-outflow still.

Both models need observational evidence. Gravitational collapse has been searched from the very beginning of star formation studies. Recent development in technology has boosted the search of the inflow motion. A number of high-mass collapse candidates were obtained. The collapse signatures seem more common in regions with developed radiation than in younger cores, which opposes the theoretical prediction and is also very different from that of low –mass star formation. Results seem to favor the accretion model. However, to solve the radiation problem, accretion should not be isotropic. The direct evidence of such infalling is still being searched. Future work is also needed to distinguish among infall, rotation and outflow, and to identify fast and slow inflows.