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E. K. Holmes, S. F. Dermott, M. C. Wyatt (University of Florida)
There is a possible connection between structure in planetary debris disks and the presence of planets, our own zodiacal cloud being one of the prime examples. Asymmetries in such a disk could be diagnostic of planets which would be otherwise undetectable. At least three different types of asymmetries can serve to indicate bodies orbiting a star in a disk: (1) a warp in the plane of symmetry of the disk due to the variation of the forced inclinations, If, with respect to the astrocentric distance of the particles, (2) an offset in the center of symmetry of the disk with respect to the central star due to the forced eccentricities of the dust particles, and (3) density anomalies in the plane of the disk due to resonant trapping of dust particles. Dynamical models of exo-solar system disks have been constructed based on the numerical integration of asteroidal particles of a set diameter. The dynamical evolution of the particles is followed from source to sink with Poynting Robertson light drag, solar wind drag, radiation pressure, and the effects of forced elements produced by planetary gravitational perturbations included. For a two planet system, the variation in If with respect to semi-major axis, a, depends on the mass ratio, M1/M2, the ratio of the semi-major axes, a1/a2, and the mutual inclination, Imutual, of the planets. We begin to characterize the warp in two planet models by varying M1/M2, a1/a2, and Imutual. By viewing the integrated brightness along the line of sight of the models in the reference frame of an external observer for the 24, 70, and 160 micron wave bands we can investigate to what extent a warp in the disks could be seen by spacecraft missions such as SIRTF.
This research was funded in part by a NASA GSRP grant.