Showing papers on "Trojan published in 1997"

Dynamical evolution of Jupiter's Trojan asteroids

Abstract: TROJAN asteroids, which may outnumber the asteroids in the asteriod belt, are objects that orbit the Sun with the same mean semi-major axis as Jupiter, but lead or trail the position of Jupiter in its orbit by ˜60°. One very interesting aspect of the Trojan swarms is that a significant number of asteroids are on orbits that analytic theory suggests should be unstable1. Here we present the results of long-term dynamical integrations of the Trojan asteroids, that enable us to investigate the stability of the swarm population. We find that the orbits of the swarm asteroids are not stable indefinitely—the gravitational effects of the giant planets have reduced the swarms' outer boundaries over time. We estimate that there are over 200 escaped Trojan asteroids with diameters >lkm currently roaming the Solar System, a few of which may be on Earth-crossing orbits.

On the stability of the Trojan asteroids.

Abstract: We reconsider the problem of stability of the triangular Lagrangian equilibria of the restricted problem of three bodies.We consider in particular the Sun–Jupiter model and the Trojan asteroids in the neighbourhood of the point L4. In the spirit of Nekhoroshev’s theory on stability over exponentially large times, we are able to prove that stability over the age of the universe is guaranteed on a region big enough to include a few known asteroids. This significantly improves previous works on the same subject.

The Trojan problem

Abstract: There has been a renewed interest in the Trojan problem in recent years. Significant progress has been made in discovering and understanding dynamical features of motion of Jupiter’s Trojan asteroids. The dynamics of hypothetical Trojan-type asteroids of other major planets has also been the subject of several recent investigations. This paper offers an overview on the current status of researches on real and hypothetical Trojan asteroids of the major planets. Results of analytical and numerical works are surveyed. Questions of dynamical properties, long-term evolution of orbits, stability regions around the triangular Lagrangian points are discussed among other problems of the Trojans.

Radiative decay of Trojan wave packets

Abstract: It has been recently shown theoretically @1‐6# that in highly excited atoms placed in a strong, resonant circularly polarized electromagnetic wave there exist dressed electronic states in the form of nonstationary, nonspreading wave packets, called Trojan wave packets @1#. These states are highly stable against ionization @5# with a lifetime of about 10 6 Kepler periods for wave packets corresponding to n560. In the present paper we calculate the decay rate of Trojan wave packets due to spontaneous emission and show that this process is much slower that the ionization. The concept of Trojan states has been further generalized @7‐11# by adding the magnetic field to achieve an even stronger stabilization of the wave packets. However, in the present paper we do not consider the influence of the magnetic field. In order to perform the calculation of the lifetime, we have to generalize the standard method based on the Fermi golden rule, as shown in @12#, to deal with transitions between nonstationary, rotating states. The dynamics of Trojan wave packets interacting with the quantized electromagnetic field is governed by the Hamiltonian