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Session 41 - T Tauri Stars & Protostellar Regions.
Display session, Wednesday, June 11
South Main Hall,

[41.02] Three Dimensional Hydrodynamic Instabilities in Protostellar Disks with Cooling

B. K. Pickett, P. Cassen (NASA/ARC), R. H. Durisen, R. Link (Indiana U.)

We present a series of extended three dimensional hydrodynamics calculations of protostellar cores in order to investigate the role of thermal energetics. One set of protostellar core models, denoted Hot Models, are isentropic equilibrium states formed by the axisymmetric collapse of uniformly rotating singular isothermal spheres. These objects are continuous star/disk systems, in which the star, the disk, and the star/disk boundary can be resolved in 3D in our hydrodynamics code. Since the disks of these equilibria are forced to have the same entropy as the stars, they are hotter than is typically considered appropriate for protostellar disks. Thus, the second set of models, denoted Cooled Models, are generated by first cooling the Hot Models in axisymmetry, and then calculating their subsequent nonaxisymmetric evolution. We compare evolutions of the Hot and Cooled models in which the disk is treated both adiabatically and isothermally, representing two extremes in cooling. The Hot models are marginally unstable to spiral disturbances that do not alter the protostellar core over many rotation periods. The Cooled models are highly unstable to multiple spirals, particularly two-armed spirals, which transport significant angular momentum and mass in a few dynamical times. In the isothermal evolution, the instability leads to the disruption of the disk and concentration of material into several dense, thin arcs. We compare these calculations with previous results and discuss the implications for star and solar system formation.

This research is supported by grants NAGW-3399 DURISEN and RTOP 344-30-5101 CASSEN.

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