scholarly journals A dynamical study of the Gefion asteroid family

2019 ◽  
Vol 622 ◽  
pp. A39 ◽  
Author(s):  
S. Aljbaae ◽  
J. Souchay ◽  
A. F. B. A. Prado ◽  
T. G. G. Chanut
Keyword(s):  
Target Function ◽  
Orbital Plane ◽  
Major Axis ◽  
Symplectic Integrators ◽  
Ejection Velocity ◽  
Semi Major Axis ◽  
Dynamical Study ◽  
Mean Motion Resonances ◽  
Yorp Effect ◽  
The Right

The Gefion asteroid family is a group of S-type asteroids located between the 8J:-3A and 5J:-2A mean-motion resonances. The 5J:-2A resonance seems to be responsible for the absence of the right side of the V-shape of this family. We aim in this work to present a detailed study on the Gefion family, motivated by the incompatibility found in previous family age estimations and the fact that this family could be seen as one of the most probable sources of L-chondrite meteorites. After eliminating all possible taxonomical and dynamical interlopers, we use a Monte Carlo method to analyze the semi-major axis evolution of several fictitious families under the influence of the Yarkovsky and Yarkovsky-O’Keefe-Radzievsky-Paddack (YORP) effects. We also perform simulations using symplectic integrators to account for the Yarkovsky effect (diurnal and seasonal versions) and the stochastic YORP effect. We make use of the distribution of the component of the ejection velocity field (vW) perpendicular to the orbital plane and the time dependence of the asymmetry of the distribution of the target function of a fictitious family generated with ejection velocity parameter 20+55−15 m s−1 to obtain an age estimate of 1030+19−67 Myr. We find that 6.5% of asteroids from the Gefion family can reach orbits similar to particles in the current near-Earth objects space; 73% of them are among the Amors asteroids, and the remaining ones are among the Apollos. We only found 0.5% from the Gefion family reaching the Mars-crossing space.

Effect of an oblate rotating atmosphere on the orientation of a satellite orbit

1961 ◽  
Vol 261 (1305) ◽  
pp. 246-258 ◽  
Keyword(s):  
Orbital Plane ◽  
Satellite Orbit ◽  
Major Axis ◽  
Earth Satellite ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
Small Eccentricity ◽  
Earth Satellite Orbit ◽  
The Right ◽  
Right Ascension

For an earth satellite orbit of small eccentricity ( e < 0·2) formulae are derived for the changes per revolution produced by the atmosphere in the argument of perigee, in the right ascension of the ascending node, and in the orbital inclination. These changes are then expressed in terms of the change in length of the semi-major axis, and numerical values are obtained for satellite 1957 β . It is found that the rotation of the major axis in the orbital plane due to the atmosphere is significant, being most important for inclinations between 60 and 70°. The total rotation, due both to the gravitational potential and to the atmosphere, agrees reasonably well with the observed values. The oblateness of the atmosphere is found to have only a small effect on the changes in the orbital inclination and the right ascension of the ascending node.

scholarly journals Interaction between Yarkovsky force and mean-motion resonances: Some specific properties

2016 ◽  
pp. 19-26 ◽  
Author(s):  
I. Milic-Zitnik
Keyword(s):  
Time Delays ◽  
Functional Relationship ◽  
Major Axis ◽  
Asymmetric Distribution ◽  
Orbital Eccentricity ◽  
Semi Major Axis ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Drift Speed

Recently, we analyzed the role of mean-motion resonances in semi-major axis mobility of asteroids, and established a functional relationship that describes the dependence of the average time spent inside the resonance on the strength of this resonance and the semi-major axis drift speed. Here we extend this analyzis in two directions. First, we study the distribution of time delays inside the resonance and found that it could be described by the modified Laplace asymmetric distribution. Second, we analyze how the time spent inside the resonance depends on orbital eccentricity, and propose a relation that allows to take into account this parameter as well.

scholarly journals Ring dynamics around an oblate body with an inclined satellite: the case of Haumea

2020 ◽  
Vol 643 ◽  
pp. A67
Author(s):  
Francesco Marzari
Keyword(s):  
Equatorial Plane ◽  
Protective Factor ◽  
Central Body ◽  
Orbital Plane ◽  
Major Axis ◽  
The Body ◽  
Triaxial Ellipsoid ◽  
Semi Major Axis ◽  
Short Timescale ◽  
The Impact

Context. The recent discovery of rings and massive satellites around minor bodies and dwarf planets suggests that they may often coexist, as for example around Haumea. Aims. A ring perturbed by an oblate central body and by an inclined satellite may disperse on a short timescale. The conditions under which a ring may survive are explored both analytically and numerically. Methods. The trajectories of ring particles are integrated under the influence of the gravitational field of a triaxial ellipsoid and (a) massive satellite(s), including the effects of collisions. Results. A ring initially formed in the equatorial plane of the central body will be disrupted if the satellite has an inclination in the Kozai–Lidov regime (39.2° < i < 144.8). For lower inclinations, the ring may relax to the satellite orbital plane thanks to an intense collisional damping. On the other hand, a significant J2 term easily suppresses the perturbations of an inclined satellite within a critical semi-major axis, even in the case of Kozai–Lidov cycles. However, if the ring is initially inclined with respect to the equatorial plane, the same J2 perturbations are not a protective factor but instead disrupt the ring on a short timescale. The ring found around Haumea is stable despite the rise in the impact velocities that is due to the asymmetric shape of the body and the presence of a 3:1 resonance with the rotation of the central body. Conclusions. A ring close to an oblate central body should be searched for in the proximity of the equatorial plane, where the J2 perturbations protect it against the perturbations of an external inclined satellites. In an inclined configuration, the J2 term is itself disruptive.

scholarly journals Dynamical Behaviour of Asteroids in the 4:1 Resonance

1999 ◽  
Vol 172 ◽  
pp. 377-378 ◽  
Author(s):  
Francisco López-García ◽  
Adrian Brunini
Keyword(s):  
Time Scale ◽  
Initial Conditions ◽  
Major Axis ◽  
Orbital Evolution ◽  
Dynamical Behaviour ◽  
Three Dimensions ◽  
Symplectic Integrators ◽  
Minor Planets ◽  
Semi Major Axis ◽  
Secular Resonance

We study the dynamics of mean motion resonance with Jupiter in the 4:1 gap using only gravitational methods. This mechanism is capable of explaining this Kirkwood gap in an uniform way (see Ferraz-Mello, 1994; Ferraz-Mello et al., 1994; Moons, 1997; Yoshikawa, 1989). We considered the asteroidal motion in two and three dimensions and we carried out our investigations integrating numerically the full equations of motion and taking into account Mars, Jupiter and Saturn as disturbing planets. The orbital evolution of asteroids was obtained considering the elements variation. The numerical investigations were carried out using symplectic integrators. These integrations were stopped when the asteroid had close encouters with Mars or Jupiter, this occurs when the distance between the planet and the asteroid is of the order of 0.01 AU or less, or when the eccentricity increases up to 0.9. We studied real and fictitious asteroids on a time scale of 5 × 107 yr. The initial osculating elements of perturbing planets and their inverse masses were taken from the Ephemerides of Minor Planets (EMP) at the epoch of JD 2450000.5. The initial data corresponding to the real asteroids were also taken from the EMP. The starting elements of fictitious asteroids were, in all analyzed cases, a = acrit = 2.064; AU, i = 2°.5 and e = 0.01 (in the majority of cases). The other initial elements are shown in Table II. We have also studied fictitious asteroids with i = 0°, a = acrit and e = 0.01 (Table I). The present analysis leads to the following results: (1) The motions are unstable. The eccentricity, in the majority of cases, has very large increase. It may grow up to 0.9 in 106 yr. The semi major axis has large variations then, owing to both effects some fictitious asteroids reach the 3:1 resonance while others reach 7:2 resonance in a few million years, they are very chaotic regions. (2) The eccentricities of fictitious asteroids become large by the effect of the secular resonance v6, i.e. when (ϖ − ϖSat) ≅ 0, the rate of this resonance is 26.217”/year with period ~ 4.9 × 104 years (Bretagnon, 1974). (3) The fictitious asteroids studied with a = acrit, e < 0.05 and i < 3° are removed of this gap mainly by the effects of the secular resonances v6 and v16 (see Moons and Morbidelli, 1995; Williams, 1969). (4) There are close encounters with Mars or eventually with the Earth (not considered here) in a time scale of 106 - 107 yr. (5) For certain initial conditions some fictitious asteroids are temporally captured by Mars and in some cases for a long time. (6) If a = acrit,e = 0.3 and the inclination is less than 3°, Mars and asteroid’s perihelion are very close ( ~ 0.06AU ). This situation helps the capture. (7) The (a,e)-plane was used to determine the dynamical behaviour of all asteroids and we found that the 4:1 resonance is very strong. The Lyapunov times are very short.

scholarly journals HD 83443: a system with two Saturns

2004 ◽  
Vol 202 ◽  
pp. 84-86 ◽  
Author(s):  
M. Mayor ◽  
D. Naef ◽  
F. Pepe ◽  
D. Queloz ◽  
N. C. Santos ◽  
...  
Keyword(s):  
Planetary System ◽  
Major Axis ◽  
Giant Planets ◽  
Outer Planet ◽  
Semi Major Axis ◽  
Dynamical Study ◽  
Low Mass ◽  
The Stability ◽  
Extrasolar Planetary System

We report the discovery of an extrasolar planetary system with two Saturnian planets around the star HD 83443. The new planetary system is unusual by more than one aspect, as it contains two very low–mass gaseous giant planets, both on very tight orbits. Among the planets detected so far, the inner planet has the smallest semi–major axis (0.038 AU) and period (2.985 days) whereas the outer planet is the lightest one with m2 sin i = 0.53 MSat. A preliminary dynamical study confirms the stability of the system.

Effect of J3 perturbation on satellite position in LEO

2018 ◽  
Vol 90 (1) ◽  
pp. 74-86
Author(s):  
Nai-ming Qi ◽  
Qilong Sun ◽  
Yong Yang
Keyword(s):  
Satellite Orbit ◽  
Major Axis ◽  
Variation Method ◽  
Semi Major Axis ◽  
Content Type ◽  
The Difference ◽  
The Right ◽  
Perturbation Effect ◽  
Earth’S Oblateness ◽  
Right Ascension

Purpose The purpose of this paper is to study the effect of J3 perturbation of the Earth’s oblateness on satellite orbit compared with J2 perturbation. Design/methodology/approach Based on the parametric variation method in the time domain, considering more accurate Earth potential function by considering J3-perturbation effect, the perturbation equations about satellite’s six orbital elements (including semi-major axis, orbit inclination, right ascension of the ascending node, true anomaly, eccentricity and argument of perigee) has been deduced theoretically. The disturbance effects of J2 and J3 perturbations on the satellite orbit with different orbit inclinations have been studied numerically. Findings With the inclination increasing, the maximum of the semi-major axis increases weakly. The difference of inclination disturbed by the J2 and J3 perturbation is relative to orbit inclinations. J3 perturbation has weak effect on the right ascension and argument of perigee. The critical angle of the right ascension and argument of perigee which decides the precession direction is 90° and 63.43°, respectively. The disturbance effects of J2 and J3 perturbations on the argument of perigee, right ascension and eccentricity are weakened when the eccentricity increases, simultaneously, the difference of J2 and J3 perturbations on argument of perigee, right ascension and argument of perigee decreases with eccentricity increasing, respectively. Practical implications In the future, satellites need to orbit the Earth much more precisely for a long period. The J3 perturbation effect and the weight compared to J2 perturbation in LEO can provide a theoretical reference for researchers who want to improve the control accuracy of satellite. On the other hand, the theoretical analysis and simulation results can help people to design the satellite orbit to avoid or diminish the disturbance effect of the Earth’s oblateness. Originality/value The J3 perturbation equations of satellite orbit elements are deduced theoretically by using parametric variation method in this paper. Additionally, the comparison studies of J2 perturbation and J3 perturbation of the Earth’s oblateness on the satellite orbit with different initial conditions are presented.

scholarly journals Dynamical evolution of asteroid pairs in the vicinity of resonances

2021 ◽  
Author(s):  
A. E. Potoskuev ◽  
◽  
E. D. Kuznetsov ◽  
Keyword(s):  
Equations Of Motion ◽  
Dynamical Evolution ◽  
Major Axis ◽  
Time Interval ◽  
Orbital Elements ◽  
Semi Major Axis ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Yarkovsky Effect ◽  
Numerical Integrations

Dynamical evolution of asteroid pairs in close orbits near Jovian mean motion resonances (3 : 1, 4 : 1, 5 : 2, 7 : 3) has been researched by means of numerical integrations of the equations of motion over 1 Myr time interval in the future. Initial orbital elements’ uncertainty and semi-major axis drift due to the Yarkovsky effect significantly affect orbit modification with time, especially for objects originally situated in the vicinity of resonances. Passing through a resonance generally leads to orbital distance growth.

scholarly journals Regions of Stability of Asteroids

1983 ◽  
Vol 74 ◽  
pp. 123-136 ◽  
Author(s):  
Victor Szebehely ◽  
Raimundo Vicente ◽  
John Lundberg
Keyword(s):  
Restricted Problem ◽  
Three Dimensional ◽  
Orbital Plane ◽  
Major Axis ◽  
Orbital Elements ◽  
Semi Major Axis ◽  
Orbital Parameters ◽  
Regions Of Stability ◽  
Conditions Of Stability ◽  
Perihelion Passage

AbstractUsing Hill's modified stability criterium, regions of orbital elements are established for conditions of stability. The model of the three-dimensional restricted problem of three bodies is used with the Sun and Jupiter as the primaries. Four different cases are studied: direct and retrograde, outside and inside asteroidal orbits. The directions of the asteroidal orbits refer to the synodical reference frame and the positions refer to Jupiter's orbit. The orbital parameters of the asteroids are the semi-major axis (a), the eccentricity (e), and the inclination from Jupiter's orbital plane (i). The effects of the other orbital elements are not investigated in this paper. The argument of the perihelion and the longitude of the ascending node are fixed at Ω = ω = 90° and the time of perihelion passage is T = 0 for all orbits.

scholarly journals Influence of stellar structure, evolution, and rotation on the tidal damping of exoplanetary spin-orbit angles

2018 ◽  
Vol 618 ◽  
pp. A90 ◽  
Author(s):  
C. Damiani ◽  
S. Mathis
Keyword(s):  
Initial Conditions ◽  
Orbital Plane ◽  
Major Axis ◽  
Stellar Model ◽  
Convective Zone ◽  
Stellar Structure ◽  
Structure Evolution ◽  
Semi Major Axis ◽  
Tidal Evolution ◽  
Magnetic Braking

Context. It is debated whether close-in giant planets can form in-situ and if not, which mechanisms are responsible for their migration. One of the observable tests for migration theories is the current value of the obliquity, that is, the angle between the stellar equatorial plane and the orbital plane. However, after the main migration mechanism has ended, the obliquity and the semi-major axis keep on evolving due to the combined effects of tides and magnetic braking. The observed correlation between effective temperature and measured projected obliquity in well-characterised systems has been taken as evidence of such mechanisms being at play. Aims. Our aim is to produce an improved model for the tidal evolution of the obliquity, including all the components of the dynamical tide for circular misaligned systems. This model is developed to take into account the strong variations in structure and rotation of stars during their evolution, and their consequences for the efficiency of tidal dissipation. Methods. Our model uses an analytical formulation for the frequency-averaged dissipation in convective layers for each mode, depending only on global stellar parameters and rotation. It also includes the effect of magnetic braking in the framework of a double zone stellar model. Results. For the orbital configurations of typical hot Jupiters, the obliquity is generally damped on a much shorter timescale than the semi-major axis. The final outcome of tidal evolution is also very sensitive to the initial conditions, with Jupiter-mass planets being either quickly destroyed or put on more distant orbits, depending on the initial ratio of planetary orbital momentum to stellar spin momentum. However, we find that everything else being the same, the evolution of the obliquity around low-mass stars with a thin convective zone is not slower than around those with a thicker convective zone. On the contrary, we find that more massive stars, which remain faster rotators throughout their main-sequence, produce more efficient dissipation.

Detection and Characterization of earth-like Planets

1997 ◽  
Vol 161 ◽  
pp. 299-311 ◽  
Author(s):  
Jean Marie Mariotti ◽  
Alain Léger ◽  
Bertrand Mennesson ◽  
Marc Ollivier
Keyword(s):  
Direct Detection ◽  
Contrast Ratio ◽  
Angular Size ◽  
Physical Nature ◽  
Major Axis ◽  
Infrared Emission ◽  
Space Technology ◽  
Semi Major Axis ◽  
Earth Like Planets ◽  
Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

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