98 research outputs found
Sur la dynamique coorbitale : du mouvement des troyens de Jupiter à la rotation des plan etes coorbitales
Le premier chapitre présentera les principales techniques sur lesquelles sont basés les travaux exposés dans ce mémoire : l'étude de l'application fréquence, la mesure de la diffusion par analyse en fréquence et l'application de ces dernières à l'étude de la dynamique globale d'un système planétaire. Dans le deuxième chapitre, je proposerai une introduction à la résonance coorbitale. Après avoir exposé quelques aspects historiques de l'existence d'orbites remarquables dans le problème des trois corps (non restreint), je rappellerai certains points concernant la stabilité de ces solutions, puis présenterai des résultats originaux ayant trait au problème moyen ainsi qu'aux bifurcations des équilibres de Lagrange et d'Euler. Après avoir abordé la résonance coorbitale dans le cadre du problème des 3-corps, j'exposerai, dans le troisième chapitre, les résultats obtenus sur la dynamique des troyens de Jupiter, ainsi que certaines de leurs extensions. Les trajectoires des troyens seront étudiés à l'aide du problème restreint de (n+2)-corps, n correspondant au nombre de planètes du système auxquelles on ajoutera le Soleil et une particule test représentant le troyen. L'essentiel du travail consistera à comprendre les structures dynamiques des essaims dans l'espace des fréquences. Les résultats découleront naturellement de cette étude. Je donnerai d'abord une classification des principales résonances conditionnant la dynamique des essaims. Je montrerai ensuite comment cette structure résonante influence la dynamique à long terme des essaims de Jupiter et en particulier leur érosion engendrée par des phénomènes de diffusion. Je terminerai ce chapitre en abordant la question de la modification de la structure résonante, et par conséquent de la stabilité de l'essaim, sous l'effet de la modification de la géométrie du système planétaire.Le quatrième chapitre regroupera mes travaux effectués sur la rotation des corps en résonance coorbitale.Je débuterai ce chapitre en présentant l'approche générale de la rotation en résonance coorbitale qui nous a conduit à distinguer trois grandes classes dynamiques de systèmes en fonction de leurs masses et des valeurs des moments d'inertie des corps qui les composent. Pour deux de ces classes apparaît un nouveau type de résonance spin-orbit qui peut conduire à des rotations chaotiques. Pour l'autre classe, à laquelle appartiennent les satellites de Saturne Janus, Epiméthée, Hélène, Polydeuces, Téthys et Calypso, on retrouvera les résonances spin-orbit habituelles perturbées par le mouvement coorbital. C'est à la rotation de ces six satellites que seront consacrés les derniers paragraphes du quatrième chapitre. Je terminerai cet exposé en proposant quelques extensions et applications possibles des travaux et méthodes présentés dans ce mémoire
On the co-orbital motion in the planar restricted three-body problem: the quasi-satellite motion revisited
In the framework of the planar and circular restricted three-body problem, we
consider an asteroid that orbits the Sun in quasi-satellite motion with a
planet. A quasi-satellite trajectory is a heliocentric orbit in co-orbital
resonance with the planet, characterized by a non zero eccentricity and a
resonant angle that librates around zero. Likewise, in the rotating frame with
the planet it describes the same trajectory as the one of a retrograde
satellite even though the planet acts as a perturbator. In the last few years,
the discoveries of asteroids in this type of motion made the term
"quasi-satellite" more and more present in the literature. However, some
authors rather use the term "retrograde satellite" when referring to this kind
of motion in the studies of the restricted problem in the rotating frame. In
this paper we intend to clarify the terminology to use, in order to bridge the
gap between the perturbative co-orbital point of view and the more general
approach in the rotating frame. Through a numerical exploration of the
co-orbital phase space, we describe the quasi-satellite domain and highlight
that it is not reachable by low eccentricities by averaging process. We will
show that the quasi-satellite domain is effectively included in the domain of
the retrograde satellites and neatly defined in terms of frequencies.
Eventually, we highlight a remarkable high eccentric quasi-satellite orbit
corresponding to a frozen ellipse in the heliocentric frame. We extend this
result to the eccentric case (planet on an eccentric motion) and show that two
families of frozen ellipses originate from this remarkable orbit.Comment: 30 pages, 13 figures, 1 tabl
Spin-orbit coupling and chaotic rotation for coorbital bodies in quasi-circular orbits
Coorbital bodies are observed around the Sun sharing their orbits with the
planets, but also in some pairs of satellites around Saturn. The existence of
coorbital planets around other stars has also been proposed. For close-in
planets and satellites, the rotation slowly evolves due to dissipative tidal
effects until some kind of equilibrium is reached. When the orbits are nearly
circular, the rotation period is believed to always end synchronous with the
orbital period. Here we demonstrate that for coorbital bodies in quasi-circular
orbits, stable non-synchronous rotation is possible for a wide range of mass
ratios and body shapes. We show the existence of an entirely new family of
spin-orbit resonances at the frequencies , where is the
orbital mean motion, the orbital libration frequency, and an integer.
In addition, when the natural rotational libration frequency due to the axial
asymmetry, , has the same magnitude as , the rotation becomes
chaotic. Saturn coorbital satellites are synchronous since , but
coorbital exoplanets may present non-synchronous or chaotic rotation. Our
results prove that the spin dynamics of a body cannot be dissociated from its
orbital environment. We further anticipate that a similar mechanism may affect
the rotation of bodies in any mean-motion resonance.Comment: 6 pages. Astrophysical Journal (2013) 6p
Rigorous treatment of the averaging process for co-orbital motions in the planetary problem
We develop a rigorous analytical Hamiltonian formalism adapted to the study
of the motion of two planets in co-orbital resonance. By constructing a complex
domain of holomorphy for the planetary Hamilto-nian, we estimate the size of
the transformation that maps this Hamil-tonian to its first order averaged over
one of the fast angles. After having derived an integrable approximation of the
averaged problem, we bound the distance between this integrable approximation
and the averaged Hamiltonian. This finally allows to prove rigorous theorems on
the behavior of co-orbital motions over a finite but large timescale
The family of Quasi-satellite periodic orbits in the circular co-planar RTBP
In the circular case of the coplanar Restricted Three-body Problem, we
studied how the family of quasi-satellite (QS) periodic orbits allows to define
an associated libration center. Using the averaged problem, we highlighted a
validity limit of this one: for QS orbits with low eccentricities, the averaged
problem does not correspond to the real problem. We do the same procedure to L
3 , L 4 and L 5 emerging periodic orbits families and remarked that for very
high eccentricities F L4 and F L5 merge with F L3 which bifurcates to a stable
family
The resonant structure of Jupiter's trojan asteroids-II. What happens for different configurations of the planetary system.
In a previous paper, we have found that the resonance structure of the present Jupiter Trojan swarms could be split up into four different families of resonances. Here, in a first step, we generalize these families in order to describe the resonances occurring in Trojan swarms embedded in a generic planetary system. The location of these families changes under a modification of the fundamental frequencies of the planets and we show how the resonant structure would evolve during a planetary migration. We present a general method, based on the knowledge of the fundamental frequencies of the planets and on those that can be reached by the Trojans, which makes it possible to predict and localize the main events arising in the swarms during migration. In particular, we show how the size and stability of the Trojan swarms are affected by the modification of the frequencies of the planets. Finally, we use this method to study the global dynamics of the Jovian Trojan swarms when Saturn migrates outwards. Besides the two resonances found by Morbidelli et al (2005) which could have led to the capture of the current population just after the crossing of the 2:1 orbital resonance, we also point out several sequences of chaotic events that can influence the Trojan population
Trojan Exoplanets
Co-orbital exoplanets are a by-product of the models of formation of
planetary systems. However, none have been detected in nature thus far.
Although challenging, the observation of co-orbital exoplanets would provide
valuable information on the formation of planetary systems as well as on the
interactions between planets and their host star. After a brief review of the
stability and formation issues of co-orbital systems, some observational
methods dedicated to their detection are presented.Comment: Hans Deeg \S Juan Antonio Belmonte. Handbook of Exoplanets, 2nd
Edition, Springer International Publishing AG, part of Springer Nature, In
pres
Spin-orbit resonances and rotation of coorbital bodies in quasi-circular orbits
The rotation of asymmetric bodies in eccentric Keplerian orbits can be
chaotic when there is some overlap of spin-orbit resonances. Here we show that
the rotation of two coorbital bodies (two planets orbiting a star or two
satellites of a planet) can also be chaotic even for quasi-circular orbits
around the central body. When dissipation is present, the rotation period of a
body on a nearly circular orbit is believed to always end synchronous with the
orbital period. Here we demonstrate that for coorbital bodies in quasi-circular
orbits, stable non-synchronous rotation is possible for a wide range of mass
ratios and body shapes. We further show that the rotation becomes chaotic when
the natural rotational libration frequency, due to the axial asymmetry, is of
the same order of magnitude as the orbital libration frequency
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