Dr. Chris McKee
UC Berkeley

University of Florida Astronomy Colloquium - May 10th, 2006

The Formation of Massive Stars

Massive stars generate most of the heavy elements in the universe and have a dominant influence on the evolution of galaxies. Such stars form in dense regions of molecular clouds that have surface densities of order 1 g/cm^2; this is similar to the surface density both of contemporary star clusters that contain massive stars and of globular clusters, which had massive stars in the distant past. The turbulent core model for massive star formation predicts that massive stars form in regions of molecular gas that are highly turbulent on a time scale of about 10^5 yr. The corresponding accretion rate is high enough to overcome the radiation pressure due to the luminosity of the star. Ongoing numerical simulations are consistent with this theoretical picture and show that three-dimensional effects allow massive protostars to continue accreting material at high luminosities. Analysis of the spectral energy distributions of the radiation emitted by massive protostars provides a powerful diagnostic for determining the physical conditions in which massive stars form.