April 12, 1999 CfA Colloquium

Title: Toward a Theory of Isolated Binary-Star Formation

Speaker: Frank Shu

Abstract: During the past two decades, substantial observational and theoretical progress has been made on the study of the formation of isolated single stars. Much less is known about binary star formation, although speculations have existed for more than a century concerning relevant mechanisms. Both the fission and fragmentation hypotheses have difficulties when no dynamical role is given to magnetic fields. We discuss how current notions about molecular cloud-core structure and collapse relate to the earlier ideas, and suggest a solution on the basis of a rapid decoupling of the magnetic field during the dense phases of the anisotropic gravitational collapse. A key element to making theoretical calculations to support this proposal is the existence of a much wider class of non-axisymmetric, self-gravitating, magnetized equilibria that can represent realistic pre-collapse states than had been previously suspected.

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