Computer Science – Numerical Analysis
Scientific paper
Nov 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...436..335l&link_type=abstract
Astrophysical Journal, Part 1 (ISSN 0004-367X), vol. 436, no. 1, p. 335-354
Computer Science
Numerical Analysis
168
Angular Momentum, Axisymmetric Bodies, Computerized Simulation, Hydrodynamics, Numerical Analysis, Stellar Evolution, Stellar Models, Gravitational Effects, Kepler Laws
Scientific paper
We present a two-dimensional, multi-gridded hydrodynamical simulation of the collapse of an axisymmetric, rotating, 1 solar mass protostellar cloud, which forms a resolved, hydrotastic disk. The code includes the effects of physical viscosity, radiative transfer and radiative acceleration but not magnetic fields. We examine how the disk is affected by the inclusion of turbulent viscosity by comparing a viscous simulation with an inviscid model evolved from the same initial conditions, and we derive a disk evolutionary timescale on the order of 300,000 years if alpha = 0.01. Effects arising from non-axisymmetric gravitational instabilities in the protostellar disk are followed with a three-dimensional SPH code, starting from the two-dimensional structure. We find that the disk is prone to a series of spiral instabilities with primary azimuthal mode number m = 1 and m = 2. The torques induced by these nonaxisymmetric structures elicit material transport of angular momentum and mass through the disk, readjusting the surface density profile toward more stable configurations. We present a series of analyses which characterize both the development and the likely source of the instabilities. We speculate that an evolving disk which maintains a minimum Toomre Q-value approximately 1.4 will have a total evolutionary span of several times 105 years, comparable to, but somewhat shorter than the evolutionary timescale resulting from viscous turbulence alone. We compare the evolution resulting from nonaxisymmetric instabilities with solutions of a one-dimensional viscous diffusion equation applied to the initial surface density and temperature profile. We find that an effective alpha-value of 0.03 is a good fit to the results of the simulation. However, the effective alpha will depend on the minimum Q in the disk at the time the instability is activated. We argue that the major fraction of the transport characterized by the value of alpha is due to the action of gravitational torques, and does not arise from inherent viscosity within the smoothed particle hydrodynamics method.
Bodenheimer Peter
Laughlin Gregory
No associations
LandOfFree
Nonaxisymmetric evolution in protostellar disks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nonaxisymmetric evolution in protostellar disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonaxisymmetric evolution in protostellar disks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1022683