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[16.01] Io's Secular Acceleration vs. Observational Accuracy

V. Lainey (Obs. Royal de Belgique), G. Tobie (LPL, University of Arizona)

The tremendous heat flow emitted from the surface of Jupiter's moon Io, associated with striking volcanic activities, is thought to be the product of strong tidal dissipation within its interior. A significant acceleration on its mean motion should be observed if Io loses more orbital energy from dissipation than it gains from Jupiter's orbital tidal torque. Although the quest of tidal accelerations among the Galilean satellites has begun since the beginning of the last century (de Sitter 1928), no real agreement has been found yet. Using a numerical approach, we simulate the effect of tidal interactions on the evolution of Io's mean motion during the last century and we show how these tidal effects can be vanished during the reduction process of observational data. By testing different values of dissipation within Io and Jupiter, we show that the non-detection of significant Io's acceleration does not imply a large dissipation within Jupiter, and we propose an upper bound value for the dissipation rate within Io.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.