29 research outputs found
Tidal evolution of close-in exoplanets in co-orbital configurations
In this paper, we study the behavior of a pair of co-orbital planets, both
orbiting a central star on the same plane and undergoing tidal interactions.
Our goal is to investigate final orbital configurations of the planets,
initially involved in the 1/1 mean-motion resonance (MMR), after long-lasting
tidal evolution. The study is done in the form of purely numerical simulations
of the exact equations of motions accounting for gravitational and tidal
forces. The results obtained show that, at least for equal mass planets, the
combined effects of the resonant and tidal interactions provoke the orbital
instability of the system, often resulting in collision between the planets. We
first discuss the case of two hot-super-Earth planets, whose orbital dynamics
can be easily understood in the frame of our semi-analytical model of the 1/1
MMR. Systems consisting of two hot-Saturn planets are also briefly discussed.Comment: 18 pages, 8 figures. Accepted for publication in Celestial Mechanics
and Dynamical Astronom
Spin-orbit coupling for tidally evolving super-Earths
We investigate the spin behavior of close-in rocky planets and the
implications for their orbital evolution. Considering that the planet rotation
evolves under simultaneous actions of the torque due to the equatorial
deformation and the tidal torque, both raised by the central star, we analyze
the possibility of temporary captures in spin-orbit resonances. The results of
the numerical simulations of the exact equations of motions indicate that,
whenever the planet rotation is trapped in a resonant motion, the orbital decay
and the eccentricity damping are faster than the ones in which the rotation
follows the so-called pseudo-synchronization. Analytical results obtained
through the averaged equations of the spin-orbit problem show a good agreement
with the numerical simulations. We apply the analysis to the cases of the
recently discovered hot super-Earths Kepler-10 b, GJ 3634 b and 55 Cnc e. The
simulated dynamical history of these systems indicates the possibility of
capture in several spin-orbit resonances; particularly, GJ 3634 b and 55 Cnc e
can currently evolve under a non-synchronous resonant motion for suitable
values of the parameters. Moreover, 55 Cnc e may avoid a chaotic rotation
behavior by evolving towards synchronization through successive temporary
resonant trappings.Comment: Accepted for publication in MNRA
Modelling resonances and orbital chaos in disk galaxies. Application to a Milky Way spiral model
Context: Resonances in the stellar orbital motion under perturbations from
spiral arms structure play an important role in the evolution of the disks of
spiral galaxies. The epicyclic approximation allows the determination of the
corresponding resonant radii on the equatorial plane (for nearly circular
orbits), but is not suitable in general.
Aims: We expand the study of resonant orbits by analysing stellar motions
perturbed by spiral arms with Gaussian-shaped profiles without any restriction
on the stellar orbital configurations, and we expand the concept of Lindblad
(epicyclic) resonances for orbits with large radial excursions.
Methods: We define a representative plane of initial conditions, which covers
the whole phase space of the system. Dynamical maps on representative planes
are constructed numerically, in order to characterize the phase-space structure
and identify the precise location of resonances. The study is complemented by
the construction of dynamical power spectra, which provide the identification
of fundamental oscillatory patterns in the stellar motion.
Results: Our approach allows a precise description of the resonance chains in
the whole phase space, giving a broader view of the dynamics of the system when
compared to the classical epicyclic approach, even for objects in retrograde
motion. The analysis of the solar neighbourhood shows that, depending on the
current azimuthal phase of the Sun with respect to the spiral arms, a star with
solar kinematic parameters may evolve either inside the stable co-rotation
resonance or in a chaotic zone.
Conclusions: Our approach contributes to quantifying the domains of resonant
orbits and the degree of chaos in the whole Galactic phase-space structure. It
may serve as a starting point to apply these techniques to the investigation of
clumps in the distribution of stars in the Galaxy, such as kinematic moving
groups.Comment: 17 pages, 15 figures. Matches accepted version in A&
Tidal evolution of a close-in planet with a more massive outer companion
We investigate the motion of a two-planet coplanar system under the combined effects of mutual interaction and tidal dissipation. The secular behavior of the system is analyzed using two different approaches, restricting to the case of a more massive outer planet. First, we solve the exact equations of motion through the numerical simulation of the system evolution. We also compute the stationary solutions of the mean equations of motion based on a Hamiltonian formalism. An application to the real system CoRoT-7 is investigated.Facultad de Ciencias Astronómicas y Geofísica
Angular momentum exchange during secular migration of two-planet systems
We investigate the secular dynamics of two-planet coplanar systems evolving under mutual gravitational interactions and dissipative forces. We consider two mechanisms responsible for the planetary migration: star-planet (or planet-satellite) tidal interactions and interactions of a planet with a gaseous disc. We show that each migration mechanism is characterized by a specific law of orbital angular momentum exchange. Calculating stationary solutions of the conservative secular problem and taking into account the orbital angular momentum leakage, we trace the evolutionary routes followed by the planet pairs during the migration process. This procedure allows us to recover the dynamical history of two-planet systems and constrain parameters of the involved physical processes.Facultad de Ciencias Astronómicas y Geofísica
Tidal evolution of a close-in planet with a more massive outer companion
We investigate the motion of a two-planet coplanar system under the combined effects of mutual interaction and tidal dissipation. The secular behavior of the system is analyzed using two different approaches, restricting to the case of a more massive outer planet. First, we solve the exact equations of motion through the numerical simulation of the system evolution. We also compute the stationary solutions of the mean equations of motion based on a Hamiltonian formalism. An application to the real system CoRoT-7 is investigated.Facultad de Ciencias Astronómicas y Geofísica