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[11.05] Gas Drag Effects on the Orbital Evolution of Classical Edgeworth-Kuiper Belt Objects After an Early Stellar Encounter

H. Kobayashi, S. Ida, H. Tanaka (Dept. of Earth and Planetary Sciences, Tokyo Institute of Technology)

We show that orbital evolution due to aerodynamic gas drag after a stellar encounter can account for the observed bimodal inclination distribution of classical Edgeworth-Kuiper belt objects. We integrate orbits of the objects in classical Edgeworth-Kuiper belt region that acquire high eccentricities and inclinations by a passing stellar encounter, under the influence of gas drag of a protoplanetary disk. Even if their semimajor axes are > 40AU where disk gas density is very low, highly eccentric orbits can be affected by the gas drag because their perihelion distances are small and they pass the dense gas disk regions. The gas drag damps their eccentricities and semimajor axes, but not inclinations. Since the gas drag is more effective for smaller objects, small objects go out from the classical Edgeworth-Kuiper belt region except ones originally having small eccentricities and inclinations. On the other hand, large objects remain with small eccentricities and large inclinations. This result is consistent with the observation.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.