Featured Researcher

UC Riverside: Ken Rice

"I have been using Datastar to perform numerical simulations of self-gravitating accretion disks, in particular disks around young stars. It appears that gravitationally unstable disks may evolve either into a quasi-steady state or, if sufficiently unstable, may break up or fragment into gravitationally bound objects."

If a quasi-steady state is achieved, as shown in Figure 1, the instability acts to stably transport angular momentum, allowing mass to accrete onto the central object. This almost certainly plays an important role very early in the star formation process.

In analysing the simulations carried out on Datastar, we discovered that there is a well defined maximum stress that a quasi-steady, self-gravitating disk can achieve. If the stress exceeds this maximum value, the disk fragments—as shown in Figure 2—into gravitationally bound objects (Rice, Lodato & Armitage 2005). Such a process has been suggested both as a mechanism for forming gaseous, Jupiter-like planets in protoplanetary disks and for forming stars in disks in active galaxies."

References

Rice, W.K.M., Lodato, G. & Armitage, P.J., Investigating fragmentation conditions in self-gravitating accretion disks, Mon. Not. Roy. Astron. Soc., submitted, 2005.