Classical analytical solution for Rydberg states of muonic–electronic helium and helium-like ions

In our previous papers (Can. J. Phys. 91 (2013) 715; 92 (2014) 1405), we studied Rydberg states of systems consisting of a nucleus of charge Z, a muon, and an electron, both the muon and electron being in circular states. The studies of such quasimolecules μZe were motivated by numerous applications of muonic atoms and molecules, where one of the electrons is substituted by the heavier lepton μ–. We demonstrated that the muonic motion can represent a rapid subsystem, while the electronic motion can represent a slow subsystem. We showed that the spectral lines emitted by the muon in such systems experience a red shift compared to the corresponding spectral lines that would have been emitted by the muon in a muonic hydrogenic atom/ion. In the present paper, we also consider Rydberg states of quasimolecules μZe with Z > 1 (i.e., Rydberg states of muonic–electronic helium and helium-like ions). However, our current approach has important distinctions from our previous papers. The systems considered here are truly stable and the electron orbit is generally elliptical (although the relatively small influence of the electron on the muon is neglected). In our previous papers, the influence of the electron on the muon was taken into account; however, in the rotating frame used in our previous papers, the motion of the muon was only metastable (not truly stable), and furthermore, only circular orbits of the electron were considered in our previous paper. In the present paper, we show that the effective potential energy of the Rydberg electron is mathematically equivalent to the potential energy of a satellite moving around an oblate planet. Based on this, we demonstrate that the unperturbed orbital plane of the Rydberg electron undergoes simultaneously two different precessions: precession within the orbital plane and precession of the orbital plane around the axis of the muonic circular orbit. We provide analytical expressions for the frequencies of both precessions. The shape of the elliptical orbit of the Rydberg electron is not affected by the perturbation, which is the manifestation of the (approximate) conservation of the square of the angular momentum of the Rydberg electron. This means that the above physical systems have a higher than geometrical symmetry (also known as a hidden symmetry) which is a counterintuitive result of general physical interest. We note that the above problem of the motion of the Rydberg electron in muonic–electronic helium atoms or helium-like ions is mathematically equivalent to another problem from atomic physics: a hydrogen Rydberg atom in a linearly-polarized electric field of a high-frequency laser radiation.

Approximate analytic solution of motion for spacecraft around an oblate planet

The oblateness of a planet has an important effect on the surrounding spacecraft and is usually regarded as a significant perturbation factor to spacecraft’s motion. In this paper, an approximate analytic solution of motion for spacecraft which considering this perturbation factor is investigated. The perturbed dynamic model which taking true anomaly as the independent variable is firstly built in non-inertial coordinate system moving with a Kepler two-body orbit, then the six-dimensional state transition matrix about the state deviation vector is introduced. After that, the expression of J2 term’s gravitational potential in this non-inertial coordinate system is obtained based on spherical trigonometry, and the analytic solution for every variable of the state deviation vector is then derived by complicated mathematic transformation. Numerical simulation results done by the presented method have been compared with that done by numerical integration as well as an existing first-order analytic solution. The comparison results show that the presented method has high accuracy, and is more accurate than the first-order analytic solution within one or few orbit revolutions, which makes it more suitable for short-term orbit prediction of the satellites, especially for those suborbital flight vehicles.