Solar System Research最新文献

This paper examines the latitudinal variations in the intensity of methane and ammonia absorption bands in the near IR region of the spectrum (600–950 nm), such as CH₄ (619, 703, 727, 780, 861, 889 nm) and NH₃ (645, 790 nm). The results are presented as variations in the profiles of each of the absorption bands, their residual intensities, central depths and equivalent widths both in values obtained directly during the processing of spectrograms and in relation to the reference detail, as well as in relation to each other. The shallowest methane band at 703 nm and the deepest methane band at 886 nm give almost mirror-opposite values of absorption change along Jupiter’s central meridian. The extreme absorption values (maximum for 703 nm and minimum for 890 nm) coincide and fall on the boundary of the Equatorial Zone (EZ) and the Northern Equatorial Belt (NEB) at a relative distance of the radius of the planet’s disk r/R = 0.07. The remaining absorption bands of methane, as their intensity changes, occupy an intermediate position. As in previous years, a clearly expressed local decrease in the intensity of the NH₃ absorption bands is observed and especially centered at 787 nm at the boundary between the Equatorial Zone (EZ) and the North Equatorial Belt (NEB) compared to other regions of the central meridian. The decrease in absorption in this band begins almost from the equator, and its maximum occurs at the planetographic latitude of 10° N, then the absorption increases again, approaching the latitude of 20° N. The NH₃ absorption band at a wavelength of 645 nm also shows a decrease at low latitudes in the northern hemisphere. In the temperate latitudes of the Northern Hemisphere, absorption in this band is systematically lower than in the Southern Hemisphere. A comparison of the authors’ observations with data in the IR region and in the radio range is given, which show that the closest relationship between the brightness temperature and the absorption depth at 890 nm is observed in the upper stratosphere, in the latitude range of ±60°. Good agreement is also observed between the results of our estimates of the meridional absorption variations in the ammonia bands at 645 and 787 nm and the brightness temperature measurements performed at the VLA in the millimeter thermal emission range at frequencies of 8–12 GHz. The data for the 787-nm band in the wake region of the Great Red Spot are in particularly good agreement.

The paper examines the April chi Librids meteor shower, which is a minor meteor shower with an unidentified parent body. According to the IAU Meteor Data Center, the April chi Librids meteor shower is registered under number 140. A search for its genetic connections with near-Earth asteroid groups was conducted using an author-modified synthetic method. As a result of establishing genetic links between the April chi Librids meteor shower and near-Earth asteroids of the Apollo group, the following parent bodies were identified: 2013 YC, 2015 DU180, 2011 BT59, and 2013 WM. For the identified parent bodies, an analysis of the discovered genetic relationships was conducted using various methods.

During the periods of meteor shower maxima in 2019–2023, small variations in the intensity of solar radiation were noted (F_10.7) in fractions of a percent of the background, calculated in a sliding 5-day window. Estimates of variations in the normalized F_10.7 according to the “old” (before 2006) dates of meteor showers. With the transition to new dates of meteor shower maxima, variations in magnetic activity indices disappeared. The filtering effect of meteoric dust on the regulation of variations in solar UV radiation has been proven. An increase in the intensity of UV radiation on the dates of maxima of strong meteor showers has been confirmed by measurements in 2019 at the Russian Antarctic station Novolazarevskaya.

In this work we review and improve two useful techniques to cope with chaotic dynamics in deterministic systems, namely the Mean Exponential Growth factor of Nearby Orbits (MEGNO) and the Shannon entropy. The MEGNO provides a direct measure of the hyperbolic dynamics in an arbitrary small neighborhood of a given point of the phase space in comparatively short motion times and the maximum Lyapunov exponent (or its spectrum) can be easily derived from this fast dynamical indicator which has become a wide-spread tool in the investigation of the global dynamics in planetary systems. The time derivative of the Shannon entropy yields a confident measure of the diffusion speed in comparison with the usual approach of the action-like variance evolution. It has been successfully applied in different dynamical systems, particularly, in exoplanetary systems. A brief discussion concerning the relationship among the Shannon entropy and the Kolmogorov–Sinai or metric entropy and the topological entropy is also addressed. Both methods allow to get two relevant timescales in chaotic dynamics, the Lyapunov time and the diffusion time. An application to a simple 4D symplectic map illustrates the efficiency of both techniques.

The invariant normalization method proposed by V.F. Zhuravlev, used for calculating normal or symmetrized forms of autonomous Hamiltonian systems, is discussed. The normalizing canonical transformation is represented by a Lie series using a generating Hamiltonian. This method has a generalization proposed by A.G. Petrov, which normalizes not only autonomous but also nonautonomous Hamiltonian systems. The normalizing canonical transformation is represented by a series using a parametric function. For autonomous Hamiltonian systems, the first two approximation steps in both methods are the same, and the remaining steps are different. The normal forms of both methods are identical. A method for testing a normalization program has also been proposed. For this purpose, the Hamiltonian of a strongly nonlinear Hamiltonian system is found, for which the normal form is a quadratic Hamiltonian. The normalizing transformation is expressed in terms of elementary functions.

A space object is considered as a dynamically symmetric rigid body with a fixed point at the center of mass under the action of a periodic moment of force. Two small parameters are introduced: the first characterizes the smallness of the amplitude of the moment of force, and the second characterizes the smallness of the component of the kinetic moment perpendicular to the axis of symmetry. The smallness of the second parameter is usually the basis for using the approximate theory of the gyroscope. Using this approximation, one can quite easily find the speed of precession of the top under the action of a small periodic torque. It is shown that the relative error of the precession period calculated in this way is very small: it is proportional to the product of two small parameters. In this way, a simple formula is found for the precession of the Earth’s satellite under the influence of the Earth’s gravitational field. The resulting formula for the speed of the lunar–solar precession of the Earth agrees well with astronomical observations.

The general three-body problem is considered in shape space. Solutions to the problem in such a space have a number of remarkable properties. The paper presents the equations of motion of the three-body problem in shape space, the integrals of the problem are investigated. As it turns out, Sundman’s inequality is a simple consequence of the energy integral in the shape space. The periodic solutions obtained of the three-body problem are considered in shape space, and their properties are studied.

Abstract—A four-dimensional method of optimization of spatial-kinematic models of subsystems of objects of the Galaxy based on the principle of maximum likelihood has been proposed, taking into account the measurement and natural (dynamic) uncertainty of 3D velocities and random errors of heliocentric distances (in this case, trigonometric parallaxes). The method has been tested on masers in the high-mass star-forming regions (HMSFRs). Based on the data on these objects, new estimates of the fundamental parameters of the Galaxy were obtained, free from systematic biases due to parallax errors, in particular, the distance from the Sun to the center of the Galaxy R₀ = 7.88 ± 0.12 kpc, the angular azimuthal velocity of the Sun ({{omega }_{ odot }}) = 30.40 ± 0.20 km/s/kpc, the linear azimuthal velocity of the Sun ({{theta }_{ odot }}) = 239.6 ± 4.0 km/s/kpc.

In this paper, the authors summarize eight years of experience in the development and application of a numerical-analytical method for studying resonant structures in near-Earth and near-lunar space. The dynamics of near-Earth objects are considered in the following: orbital (tesseral) resonances of the second to tenth orders, secular apsidal-nodal resonances of the second to sixth orders, semisecular resonances with the average motion of the third body of the second to fifth orders, as well as secondary resonances arising under the influence of light pressure. In the dynamics of lunar objects, manifestations of secular and semisecular resonances are considered, and an analysis of the dynamics of low-flying objects is given.