SLING AMPLIFICATION AND ECCENTRIC GRAVITATIONAL INSTABILITIES IN GASEOUS DISKS

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

Detail(s)

Original languageEnglish
Pages (from-to)495-514
Journal / PublicationAstrophysical Journal
Volume358
Issue number2
Publication statusPublished - Aug 1990
Externally publishedYes

Abstract

Motivated by a recent study that discovered a new type of eccentric (i.e., m = 1) gravitational instability in nearly Keplerian disks, we present an analytical description of the relevant modal mechanisms. Using a WKBJ analysis, we derive a quantum condition which accurately predicts the pattern speeds (i.e., the real part of the eigenfrequencies) for these modes. One unique aspect of m = 1 modes is that the center of mass of the perturbation in the disk does not lie at the geometrical center of the system; hence, the star is displaced from the center of mass and creates an effective forcing potential - the "indirect potential." We determine the growth rates for the modes under the illustrative assumption that all of the amplification arises from the coupling of the indirect term to the outer Lindblad resonance in the disk, and that the indirect term arises mostly near the outer disk edge. We find that these modes can grow when the disk is safely stable to axisymmetric disturbances (Toomre's Q substantially greater than unity), and we discuss the case of marginal stability for these modes. We also find that the exact spectrum of unstable modes can depend on the details of the motion of the outside edge. As a benchmark, we introduce the concept of the "maximum solar nebula," which corresponds to the maximum disk mass (relative to the star mass) that remains stable to all gravitational modes. Finally, we discuss the implications of these considerations for the formation of binary companions and/or giant planets within the disks associated with young stellar objects.

Research Area(s)

  • Hydrodynamics, Stars: formation

Citation Format(s)

SLING AMPLIFICATION AND ECCENTRIC GRAVITATIONAL INSTABILITIES IN GASEOUS DISKS. / SHU, Frank H.; TREMAINE, Scott; ADAMS, Fred C. et al.

In: Astrophysical Journal, Vol. 358, No. 2, 08.1990, p. 495-514.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review