We perform numerical simulations to study the secular orbital evolution and dynamical structure of the quintuplet planetary system 55 Cancri with the self-consistent orbital solutions by Fischer and coworkers. In the ...We perform numerical simulations to study the secular orbital evolution and dynamical structure of the quintuplet planetary system 55 Cancri with the self-consistent orbital solutions by Fischer and coworkers. In the simulations, we show that this system can be stable for at least 108 yr. In addition, we extensively investigate the planetary configuration of four outer companions with one terrestrial planet in the wide region of 0.790AU 〈 a 〈 5.900AU to examine the existence of potential asteroid structure and Habitable Zones （HZs）. We show that there are unstable regions for orbits about 4：1, 3：1 and 5：2 mean motion resonances （MMRs） of the outermost planet in the system, and several stable orbits can remain at 3：2 and 1：1 MMRs, which resembles the asteroid belt in the solar system. From a dynamical viewpoint, proper HZ candidates for the existence of more potential terrestrial planets reside in the wide area between 1.0 AU and 2.3 AU with relatively low eccentricities.展开更多
The minimum energy and stable configurations in the spherical,equal mass full 4-body problem are investigated.This problem is defined as the dynamics of finite density spheres which interact gravitationally and throug...The minimum energy and stable configurations in the spherical,equal mass full 4-body problem are investigated.This problem is defined as the dynamics of finite density spheres which interact gravitationally and through surface contact forces.This is a variation of the gravitational n-body problem in which the bodies are not allowed to come arbitrarily close to each other(due to their finite density),enabling the existence of resting configurations in addition to orbital motion.Previous work on this problem has outlined an efficient and simple way in which the stability of configurations in this problem can be defined.This methodology is applied to the 4-body problem,where we find multiple resting equilibrium configurations and outline the stability of a number of these.The study of these configurations is important for understanding the mechanics and morphological properties of small rubble pile asteroids.These results can also be generalized to other configurations of bodies that interact via field potentials and surface contact forces.展开更多
GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical orbit of period 2.64 days and eccentricity 0.16. With a typical tidal dissipation factor(Q′～106) as that of a giant planet with convective env...GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical orbit of period 2.64 days and eccentricity 0.16. With a typical tidal dissipation factor(Q′～106) as that of a giant planet with convective envelope,its orbital circularization timescale under internal tidal dissipation is around 1 Ga,at least two times less than the stellar age(> 3 Ga). A plausible mechanism is that the eccentricity of GJ 436b is modulated by a planetary companion due to their mutual perturbation. Here we investigate this possibility from the dynamical viewpoint. A general method is given to predict the possible locations of the dynamically coupled companions,including nearby/distance non-resonant or mean motion resonance orbits with the first planet. Applying the method to GJ 436 system,we find it is very unlikely that the eccentricity of GJ 436b is maintained at the present location by a nearby/distance companion through secular perturbation or mean motion resonance. In fact,in all these simulated cases,GJ 436b will undergo eccentricity damp and orbital decay,leaving the present location within the stellar age. However,these results do not rule out the possible existence of planet companions in nearby/distance orbits,although they are not able to maintain the eccentricity of GJ 436b.展开更多
基金Supported by the National Natural Science Foundation of China
文摘We perform numerical simulations to study the secular orbital evolution and dynamical structure of the quintuplet planetary system 55 Cancri with the self-consistent orbital solutions by Fischer and coworkers. In the simulations, we show that this system can be stable for at least 108 yr. In addition, we extensively investigate the planetary configuration of four outer companions with one terrestrial planet in the wide region of 0.790AU 〈 a 〈 5.900AU to examine the existence of potential asteroid structure and Habitable Zones （HZs）. We show that there are unstable regions for orbits about 4：1, 3：1 and 5：2 mean motion resonances （MMRs） of the outermost planet in the system, and several stable orbits can remain at 3：2 and 1：1 MMRs, which resembles the asteroid belt in the solar system. From a dynamical viewpoint, proper HZ candidates for the existence of more potential terrestrial planets reside in the wide area between 1.0 AU and 2.3 AU with relatively low eccentricities.
文摘The minimum energy and stable configurations in the spherical,equal mass full 4-body problem are investigated.This problem is defined as the dynamics of finite density spheres which interact gravitationally and through surface contact forces.This is a variation of the gravitational n-body problem in which the bodies are not allowed to come arbitrarily close to each other(due to their finite density),enabling the existence of resting configurations in addition to orbital motion.Previous work on this problem has outlined an efficient and simple way in which the stability of configurations in this problem can be defined.This methodology is applied to the 4-body problem,where we find multiple resting equilibrium configurations and outline the stability of a number of these.The study of these configurations is important for understanding the mechanics and morphological properties of small rubble pile asteroids.These results can also be generalized to other configurations of bodies that interact via field potentials and surface contact forces.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10833001 and 10778603)the National Basic Research Program of China (Grant No. 2007CB4800)
文摘GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical orbit of period 2.64 days and eccentricity 0.16. With a typical tidal dissipation factor(Q′～106) as that of a giant planet with convective envelope,its orbital circularization timescale under internal tidal dissipation is around 1 Ga,at least two times less than the stellar age(> 3 Ga). A plausible mechanism is that the eccentricity of GJ 436b is modulated by a planetary companion due to their mutual perturbation. Here we investigate this possibility from the dynamical viewpoint. A general method is given to predict the possible locations of the dynamically coupled companions,including nearby/distance non-resonant or mean motion resonance orbits with the first planet. Applying the method to GJ 436 system,we find it is very unlikely that the eccentricity of GJ 436b is maintained at the present location by a nearby/distance companion through secular perturbation or mean motion resonance. In fact,in all these simulated cases,GJ 436b will undergo eccentricity damp and orbital decay,leaving the present location within the stellar age. However,these results do not rule out the possible existence of planet companions in nearby/distance orbits,although they are not able to maintain the eccentricity of GJ 436b.
