“Spin-orbit resonances: our Solar System in context” Alexandre Correia (University of Aveiro / Paris Observatory) IAU Symposium 276, Turin, 14 th October 2010
What is a spin-orbit resonance (SOR) ? : rotation angle ε: obliquity φ: precession angle
: longitude of the node ω Ω What is a spin-orbit resonance (SOR) ? i: inclination M: mean anomaly : longitude of the periastron
: longitude of the node What is a spin-orbit resonance (SOR) ? i: inclination M: mean anomaly : longitude of the periastron : rotation angle ε: obliquity φ: precession angle
SOR of the 1 st kind (rotation)
3/2 spin-orbit resonance (Mercury)
Capture probability P cap ~ 7%
Planetary perturbations
Correia & Laskar, Nature, (2004)
Irregular satellite Wisdom, Peale & Mignard, Icarus, (1984)
Hyperion
SOR of the 2 nd kind (precession)
Ω
Cassini states (~ 0º or ~ 180º) (0º 90º)
Saturn Ward & Hamilton, AphJ, (2004) Boué et al., AphJ, (2009)
Planetary perturbations
Earth Laskar & Robutel, Nature, (1993)
Venus Correia & Laskar, Nature, (2001)
Hot-Jupiters Correia & Laskar, Exoplanets Book, (2010) Applications to Exoplanets
Equilibrium Spin for Super-Earths Venus (aM = 0.723) GJ 581e (aM = 0.009) Arae c (aM = 0.101) Correia & Laskar, Exoplanets Book, (2010)
Conclusions Hot-Jupiters are not likely to present rotation spin-orbit resonances neither high obliquity precession spin-orbit resonances. Super-Earths tidally evolved may present rotation spin-orbit resonances, in particular when found in eccentric orbits (as Mercury). The rotation may also be chaotic as Hyperion. Super-Earths may also present high obliquities (including retrograde configurations as Venus), or even chaotic spin orientation like Mars.
“Spin-orbit resonances: our Solar System in context” Alexandre C.M. Correia (University of Aveiro) IAU Symposium 276, Turin, 14 th October 2010 Jacques Laskar (Paris Observatory)
What is a resonance? + b=0 b small b large
What is a resonance?
Capture probability Goldreich & Peale, AphJ, (1966) P cap ~ 7%
SOR of the 2 nd kind (precession) Ω
Cassini states (~ 0º or ~ 180º) (0º 90º)