Paper: astro-ph/0512150
Date: Tue, 6 Dec 2005 14:47:01 GMT (758kb)

Title: Dynamic tides in rotating objects: orbital circularisation of extra
solar planets for realistic planet models

Authors: P. B. Ivanov, J. C. B. Papaloizou

Comments: Submitted to MNRAS, resolution of several figures has been reduced
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(abbreviated) We consider the problem of the tidal capture or circularisation
from large eccentricity of a uniformly rotating object. We extend the
self-adjoint formalism introduced in Papaloizou & Ivanov 2005 (PI) to derive
general expressions for the energy and angular momentum transfered when the
planet or a star passes through periastron in a parabolic or highly eccentric
orbit around a central mass, without making a low frequency approximation as
was done in PI. We show how these can be adapted to the low frequency limit in
which only inertial modes contribute to the energy and angular momentum
transfer. We calculate the inertial mode eigenspectrum for planet models of one
and five Jupiter masses $M_J,$ without a solid core, with different radii
corresponding to different ages.

We consider the multi-passage problem when there is no dissipation finding
that stochastic instability resulting in the stochastic gain of inertial mode
energy over many periastron passages occurs under similar conditions to those
already found for the $f$ modes.

We apply our calculations to the problem of the tidal circularisation of the
orbits of the extra solar planets in a state of pseudo synchronisation, and
find that inertial mode excitation dominates the tidal interaction for $1 M_J$
planets that start with semi- major axes less than $10 AU$ and end up on
circular orbits with final period in the 4-6 day range. It is potentially able
to account for initial circularisation up to a final 6 day period within a few
$Gyr$ But in the case of $5M_J$ oscillation modes excited in the star are more
important.

\\ ( http://arXiv.org/abs/astro-ph/0512150 , 766kb)