Theoretical Studies in Star Formation

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

In this project, Dr. McKee will undertake a theoretical study of magnetic fields and their role in star formation. Magnetic fields extract angular momentum from the gas that forms a star, thereby determining whether a gas cloud forms a single star or a binary. The radiation emitted by stars as they form can suppress fragmentation, thereby enabling just one or two stars to form in a region that would have formed many in the absence of thermal feedback. For the first time, frequency-dependent radiative transfer will be used to study the effects of thermal feedback in the formation of low-mass stars. Previous theoretical research has shown that ionized regions associated with the first stars are of particular importance since they determine the masses of these stars. In addition, this project will explore the formation of stars in groups and clusters. Most stars form in clusters, and indeed it is likely that the Sun formed in a large cluster that contained high-mass stars as well as low-mass stars like the Sun. The formation of star clusters is affected by the powerful feedback mechanisms that accompany star formation, including protostellar outflows and, for massive stars, photoionization and radiation pressure. Both semi-analytic theory and simulation will be used to investigate the formation of clusters of high-mass stars. The results will be compared with observations of star clusters in the Galaxy and of super star clusters in other galaxies. Star formation on galactic scales is determined by the properties of the interstellar medium of the galaxy. Star formation is central to contemporary astrophysics. As the process by which gas is transformed into stars, it determines the structure and evolution of galaxies. By tapping the nuclear energy in the gas left over from the Big Bang, it determines the luminosity of galaxies and, quite possibly, leads to the reionization of the universe. Most of the elements, including those that make up the world around us, are formed in stars. Finally, the process of star formation is inextricably tied up with the formation and early evolution of planetary systems. A theory of star formation must address both the formation of individual stars and the formation of systems of stars, ranging from clusters to galaxies. This grant will fund the education of one or more graduate students who will contribute to education and add to the diversity of the scientific work force. Developments in computational methodology will be published for use by the community.