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2.4
Orbital dynamics of habitable extrasolar planets (Varadi, Runnegar)
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Figure
2.4. The stability of orbits of hypothetical
small planets in 3:2 orbital resonance with a giant
planet. Each dot represents a particular resonant periodic
orbit found by varying the mass and orbital eccentricity
of the giant planet. The results define paths along
which resonant periodic orbits of small planets were
determined. |
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The
known giant extrasolar planets have wide ranges of orbital semi-major
axes and eccentricities. A giant planet even with only moderately
large eccentricity sweeps a wide portion of space, colliding with
small bodies in its path, and also causes large perturbations in
the orbits of other bodies.
Can
habitable terrestrial planets survive in such orbital environments?
We have unique capabilities to locate orbitally stable regions in
extrasolar planetary systems. As opposed to the brute-force straightforward
trial-and-error numerical simulations, we map out the stable regions
of orbital resonances by computing the location and stability of
resonant periodic orbits. We already have extensive results for
the 2:3 (Varadi 1999; Figure 2.4 and the 1:2 (Haghighipour et al.
2003) orbital resonances. In the case of the former, we have found
stable, nearly circular orbits for small planets which cross the
highly eccentric orbit of a giant planet. The configuration is a
reversed analog of the one for Neptune and Pluto.
Our
technique will also be used to find stable planetary orbits in multiple-star
systems and to constrain the evolutionary path of multi-planet systems
in orbital resonances. We collaborate in this onging project.
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