Showing papers by "Scott Tremaine published in 1990"

Sling amplification and eccentric gravitational instabilities in gaseous disks

Abstract: An analytical description is presented of the modal mechanisms relevant to a recently discovered type of eccentric gravitational instability in nearly Keplerian disks. A quantum condition is derived which accurately predicts the pattern speeds for these modes. The growth rates for the modes are determined, and it is shown that the mode can grow when the disk is safely stable to axisymmetric disturbances. The case of marginal stability for the outside edge is discussed, and the implications of the results for the formation of binary companions and/or giant planets within disks associated with young stellar objects are considered.

The Local Galactic Escape Speed

Abstract: Statistical techniques for estimating the local Galactic escape speed from a uniform sample of high-velocity stars are presented for the cases of exact and uncertain observations. The former case is appropriate for high-precision radial velocities, and the latter for tangential and space velocities, which are usually derived from uncertain distances and proper motions. These two techniques have been applied to the Carney-Latham sample of high-velocity stars. It is found that the sample is too small to estimate the escape speed precisely without prior knowledge of the form of the high-velocity distribution. 23 refs.