Anti-Clockwork Planetary Systems: Long-Lived Chaotic Evolution of Mutually Inclined Exoplanets in Mean Motion Resonances
Résumé
The orbital evolution of exoplanets in mean motion resonance and with mutual inclinations is often chaotic, with large amplitude variations of eccentricity 0 up to 0.9) and inclination 0 up to 170 degrees). Despite this strongly chaotic behavior, these systems can be stable for 10 Gyr. In cases that survive for only 0.1 to 1 Gyr, eccentricities can aperiodically reach values larger than 0.999 and inclinations larger than 179.9 degrees. Typically, the orbitalbehavior appears to switch between different modes, with the classic eccentricity-type resonance as one mode. Outside of that resonance, the motion cannot be easily characterized as eccentricity- and/or inclination-type, because both operate, with the conjunction longitude librating about specific directions. This phenomenon can affect Earth-mass planets in the habitable zone, potentially altering surface habitability. Planets with eccentricities that approach unity may be tidally circularized while the inclination is at any value, revealing a previously unknown process to produce misalignment between stellarspin axes and hot planets' orbital planes. Finally, we re-examine planet-planet scattering simulations and find they produce these types of systems with a frequency of order 0.5%. Giant planets exhibiting such behavior may be detectable by the GAIA spacecraft.