Further Studies of Gravitationally Unstable Protostellar Disks
Abstract
Models of the solar nebula reveal that it might have been gravitationally unstable, both early and later in its evolution. Such instabilities produce density waves and associated gravitational torques, which are potent agents of angular momentum transport. In previous work, we conducted a series of numerical simulations designed to quantify the effects of gravitational instabilities in a generalizable way (Tomley, Cassen, & SteimanCameron 1991). Here we present a second series of simulations in which we examine disks of greater size, increased star/disk mass ratio, and flatter surface density distribution than those in our initial study. The purpose is to represent disks at a later stage of evolution than those already studied, to test the quantitative relations derived in our earlier work and to explore the effects of mass ratio on the results. The new results indicate that the tendencies for unstable, uncooled disks to heat to stability and for dynamical evolution rates to be proportional to cooling rates are general characteristics of the behavior of gravitationally unstable disks. Nevertheless, there are quantitative, and (for strong cooling) even qualitative differences that are revealed in the new simulations, particularly with regard to the cooling rates at which clumping tends to occur.
 Publication:

The Astrophysical Journal
 Pub Date:
 February 1994
 DOI:
 10.1086/173777
 Bibcode:
 1994ApJ...422..850T
 Keywords:

 Astronomical Models;
 Computerized Simulation;
 Gravitational Fields;
 Mathematical Models;
 Protostars;
 Solar Corona;
 Solar System Evolution;
 Stability;
 Star Formation;
 Stellar Envelopes;
 Clumps;
 Cooling;
 Density Distribution;
 Mass Ratios;
 Nonlinear Systems;
 Astrophysics;
 SOLAR SYSTEM: FORMATION;
 STARS: CIRCUMSTELLAR MATTER;
 STARS: FORMATION