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E. K. Holmes (National Research Council Resident Research Associate/Jet Propulsion Laboratory), C. A. Beichman (Jet Propulsion Laboratory)
There is a connection between structure in evolved circumstellar disks and the presence of planets. Asymmetries in such a disk could be diagnostic of planets that would be otherwise undetectable. Conversely, in the case of a star that possesses a planetary system, the orbital elements of the planets can be used to predict the morphology of the circumstellar disk. Three known radial velocity planets orbit Upsilon Andromedae A, the outer two of which may be in a secular apsidal resonance. The 55 Cancri system has two to three planets, one orbiting at 5.5 AU. Although a disk has not yet been observed around either Upsilon Andromedae or 55 Cancri, the upcoming Space Infrared Telescope Facility (SIRTF) mission will have unprecedented sensitivity and may reveal new infrared excesses which can be followed up with other telescopes.
In preparation for SIRTF, we have endeavored to explore the disk morphology that can be expected from these systems, if they do indeed have debris disks. We use low-order secular perturbation theory to determine the variation of the forced eccentricity and forced longitude of pericenter of particles in the disk as a function of semi-major axis, and then apply it to our circumstellar disk models. The Upsilon Andromedae disk model exhibits a noticeable asymmetry due to the apsidal alignment of the two outer planets. The 55 Cancri model exhibits an asymmetry at approximately 75 AU due to the outer planet having a non-zero forced longitude of pericenter.
This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.