11 November 2000 CfA Colloquium


Title: Dynamical Models of Turbulent, Magnetized Molecular Clouds

Speaker: Eve C. Ostriker

Abstract: Giant molecular clouds in the Galaxy are characterized by strongly supersonic internal turbulent motions, which increase in amplitude toward larger spatial scales. GMCs are also believed to contain mean magnetic fields of 10-30 microgauss in strength, such that the typical magnetic pressure substantially exceeds the thermal pressure. For some time, magnetic forces have been considered essential in supporting clouds against collapse and in slowing the turbulent dissipation rate, therefore helping to limit the galactic star formation rate. Magnetic and turbulent stresses may play a major role in shaping the internal structure of clouds, which are characterized by a hierarchy of interconnecting filaments, clumps, and voids. Recently, it has become possible to create and evolve high-resolution dynamical models of clouds using large-scale numerical MHD computations. I will present results from analyses of a set of these simulations, describing the implications for our understanding of molecular cloud evolution, and discussing the structural properties of model clouds and their relationship to tracers of density, velocity, and magnetic fields within observed GMCs.

Reference for students:

"Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models" E. C. Ostriker, J.M. Stone, & C.F. Gammie, astro-ph/0008454

Lunch with the students will be on Friday, November 17th at 12:00 in A-101.