Title:  

    The Formation of Massive Stars:  Now and Then





Chris McKee
University of California, Berkeley




Abstract:


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.
Remarkably enough, the same formalism provides an analytic
description of the formation of primordial stars.
Radiative feedback from primordial protostars is relatively
unimportant for masses less than about 30 solar masses, and
as a result the first stars were probably larger than this.