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E. K. Holmes, S. F. Dermott (University of Florida)
There is a possible connection between structure in evolved circumstellar disks and the presence of planets. Asymmetries in such a disk (such as the zodiacal cloud in the inner solar system or the Kuiper disk in the outer solar system) could be diagnostic of planets that 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, (2) an offset in the center of symmetry of the disk with respect to the central star, and (3) density anomalies in the plane of the disk such as dust bands or resonant rings. Structure in the zodiacal cloud, namely the warp and offset of the cloud, are linked to the presence of planets using secular perturbation theory. A Kuiper disk would most likely have a resonant structure, with two concentrations in brightness along the ecliptic longitude. This structure arises because 10-15% of the Kuiper belt objects, the Plutinos, are in the 3:2 mean motion resonance with Neptune (Jewitt 1999, Malhotra 1995). A size-frequency distribution of particles in the Plutino disk based on the percentage of particles that are trapped in the 3:2 resonance is determined by running numerical integrations of particles in Pluto-like orbits. The dynamical evolution of the particles is followed from source to sink with Poynting-Robertson light drag, solar wind drag, radiation pressure, the Lorentz force, neutral interstellar gas drag, and the effects of planetary gravitational perturbations included. In addition, a search is conducted in COBE DIRBE data for far-infrared emission from the Kuiper disk, which is predicted to be, at most, a few percent of the brightness of the zodiacal cloud from COBE upper limits (Dermott et al. 1999, Backman et al. 1995, Teplitz et al. 1999).