Kinematics and Physics of Celestial Bodies最新文献

A solar eclipse (SE) can cause disturbances in all subsystems of the Earth–atmosphere–ionosphere–magnetosphere system, including the geomagnetic field. Using the data obtained at 15 stations of the INTERMAGNET network, the temporal variations of all components of the geomagnetic field are analyzed. It is found that the SE has been accompanied by a disturbance of the X-, Y-, and Z-components. The largest disturbances have been detected for the X-component (south–north). There has been a steady tendency to increase the disturbance of the X-component with an increase in the area of the solar disk obscuration. The disturbance magnitude of the X-component level under the influence of the SE is calculated. It is believed that the main mechanism for generating the magnetic effect is the disturbance of the ionospheric current system at the heights of the dynamo region. The results of observations and calculations are in good agreement with each other. In addition to a stable aperiodic effect lasting approximately 100…180 min, an increase in the range of fluctuations in the geomagnetic field level has been observed during the SE. This may indicate the generation of quasi-periodic disturbances of the geomagnetic field in the range of atmospheric gravity waves.

Based on the cosmic ray transport equation, the propagation of charged high-energy particles in heliospheric magnetic fields is considered. The transport equation solution is found in the approximation of low anisotropy in the angular distribution of particles. The energy distribution of galactic cosmic rays at a heliopause is used as a boundary condition. The energy spectrum of cosmic rays in a local interstellar space is considered to be known due to the outstanding results of space missions (Pioneer, Voyager, PAMELA, AMS-02, etc.). The flux density of cosmic rays is calculated in the periods of different solar magnetic polarity. It is shown that the intensity of galactic cosmic rays in positive magnetic polarity periods is maximum near the helioequator. In the periods when the interplanetary magnetic field has a negative polarity, the intensity of cosmic rays decreases with increasing heliolatitude.

The entire spectrum of acoustic-gravity waves (AGWs), which can exist in an infinite isothermal atmosphere, is analyzed. The main attention in the study has been paid to those regions of the spectrum that are bandgaps for freely propagating waves. However, other types of waves that differ from the freely propagating AGWs in the way of propagation and in properties still may exist in these regions. Different types of bandgaps in the acoustic-gravity wave spectrum, which are found from the analysis of the dispersion equation obtained in the model of the infinite isothermal atmosphere, are studied. Classification of the types of bandgap regions in the AGW spectrum is proposed. The structure and the localization of the bandgaps relative to the regions of freely propagating waves and special points in the bandgaps of the AGW spectrum are studied using the corresponding spectral diagrams. In the bandgap region of type I, which separates the acoustic and gravity bands of freely propagating AGWs, horizontal waves with a purely imaginary value of the vertical wavenumber can exist. In the AGW spectrum, the possibility of the existence of special acoustic-gravity modes for which one of the perturbed quantities is zero has been considered and it is shown that they can exist only in the spectral bandgap of type I. A spectral bandgap in which vertical acoustic-gravity waves with a purely imaginary value of the horizontal wavenumber can exist was also analyzed. A spectral region in which the existence of acoustic-gravity waves is impossible but atmospheric oscillations may occur is also taken into consideration in this study. The properties of wave solutions in various types of spectral bandgaps, including the peculiarities of polarization ratios, are also analyzed. The theoretical analysis of spectral bandgap regions of AGWs can be used for the experimental search of new types of wave solutions in the atmosphere.

A solar eclipse (SE) leads to perturbations of all subsystems in the Earth–atmosphere–ionosphere–magnetosphere system and to perturbations of geophysical fields. Each SE leads to a whole series of physical and chemical processes occurring in the ionosphere. Along with common features, each SE has its own peculiarities with regard to these processes. These processes depend on the solar activity phase, time of the year, time of the day, geographic coordinates, atmospheric weather, space weather, magnitude of eclipse, etc. Therefore, studying these effects during each SE is an urgent task. The aim of this study is to describe the results of the analysis of the effects features of the SE which was observed shortly after sunrise on October 25, 2022 mainly at high latitudes. The data obtained from a network of space stations and navigation satellites moving over the region of partial SE were used for observations. It is found that the maximum decrease in the total electron content (TEC) in the ionosphere in these observations was 1.6–4.1 TECU, and its relative decrease reached 12–25%. The maximum decrease in the TEC was delayed 18–33 min in time with respect to the point in time when the maximum magnitude of the SE was reached. The duration of the response of the ionosphere to the SE was 120–180 min, which exceeded the eclipse duration.

In this study, we have examined the effects of small perturbations on the Coriolis force and centrifugal force in the photogravitational restricted four-body problem within the circular asteroid belt. We investigate the existence, parametric evolution, and stability of equilibrium points considering various parameters. Our findings reveal that a small perturbation in the centrifugal force significantly influences the location of equilibrium points, while a perturbation in the Coriolis force has no impact on their location. To illustrate the permissible region of motion for the infinitesimal mass relative to the Jacobi constant, we plot the zero-velocity curves. Furthermore, we conduct a comprehensive analysis to determine the influence of the Coriolis force ((alpha )) and centrifugal force ((beta )) on the geometry of the basins of convergence (BoCs). In order to quantify the unpredictability of the BoCs, we thoroughly study the basin entropy. Significantly, we have found the presence of unpredictable (fractal) regions in close proximity to the boundaries of the basins of convergence.

Solar cycle 24 began in December 2008 and ended in December 2019. Maximum of solar cycle 24 occurred in April 2014. Magnetic field intensity has been reported via data from the Wilcox Solar Observatory. Sunspot numbers are reported via the data from WDC-SILSO, Royal Observatory of Belgium. Sunspot area distribution was determined using the data from the Max Planck Institute. Flare Index intensity is indicated, and the data recorded by the Kandilli Observatory at Bogazici University is presented. Hemisphere asymmetries in terms of sunspots and solar flare index are calculated. The number of solar flares that occur at the highest intensity (X-class) during this cycle are presented, the data for which from the NOAA/SWPC. The characteristics of Coronal Mass Ejections are given, as determined using the LASCO coronagraph operating on the SOHO mission. Solar radio flux distribution and comparison with previous cycles was studied using data from Space Weather Canada.

The satellite observations of acoustic-gravity waves (AGW) in the polar atmosphere regions indicate that these waves are closely related with wind flows. This paper deals with the specific features of the propagation of acoustic-gravity waves in spatially inhomogeneous wind flows, wherein the velocity is slowly changed in the horizontal direction. A system of hydrodynamic equations taking into account the wind flow with spatial inhomogeneity is used for analysis. Unlike the system of equations written for a stationary medium (or a medium moving at a uniform velocity), the derived system contains the components describing the interaction of waves with a medium. It is shown that the effect of inhomogeneous background medium parameters can be separated from the effects of inertial forces by a special substitution of variables. An analytical expression describing the change in the amplitude of waves in a medium moving at a nonuniform velocity is derived. This expression contains two functional dependences: (1) the linear part, which is caused by the changes in the background parameters of a medium and independent of the propagation direction of waves with respect to the flow, and (2) the exponential part, which is related with inertial forces and characterizes the dependence of the amplitudes of acoustic-gravity waves on the direction of their propagation. The exponential part shows an increase in the amplitudes of waves in the headwind and a decrease in their amplitudes in the downwind. The derived theoretical dependence of the amplitudes of acoustic-gravity waves on the wind velocity is in good agreement with the data of the satellite observations of these waves in the polar atmosphere.

The results of spectropolarimetric and filter observations of a faculae region located near the solar disc center in the Fe I 1564.3, Fe I 1565.8, Ba II 455.4, and Ca II H 396.8 nm lines are discussed. The observation data are obtained using the German vacuum tower telescope of Observatorio del Teide (Tenerife, Spain). Observations of the faculae region are made simultaneously in the three spectral regions: spectropolarimetric observations of the I, Q, U, and V Stokes parameters of two neutral iron lines Fe I 1564.8 and Fe I 1565.2 nm with a time resolution of 6 min 50 s; filter observations in 37 sections of the profile of the ionized barium Ba II 455.4 nm line with a time resolution of 25.6 s; and filter observations only in the center of the ionized calcium Ca II H 396.8 nm line with a time resolution of 4.9 s. The following observation data are studied: (1) the power of the magnetic field at the altitude of the formation of a continuous spectrum near the Fe I 1564.8 and Fe I 1565.2 nm lines (h ≈ −100 km); (2) wave velocities at fourteen altitude levels in the atmosphere of the Sun, at which radiation in the Ba II 455.4 nm spectral line is formed (h ≈ 0−650 km), and calculated phase shifts Φ(V,V) between fluctuations of velocity V in the photosphere at the height of radiation formation in the center of this line (h ≈ 650 km) and velocity fluctuations at the other thirteen altitude levels; and (3) the faculae contrast at the altitude of formation of the Ca II H 396.8 nm line center (h ≈ 1600 km). The following two trends are shown: (1) The power of velocity fluctuations greatly varies depending on the frequency of oscillations with a change in the altitude in the atmosphere of the Sun. At the altitudes ranging from 0 to 300 km, the maximum oscillation power occurs at a frequency of 3.5 mHz. Another maximum occurs near a frequency of 4.5 mHz at the altitude level of h = 650 km, and the maximum oscillation power at a frequency of approximately 1.5 mHz is quite noticeable at an altitude of h = 1600 km. (2) The contrast in the center of the Ca II H 396.8 nm line (h = 650 km) does not monotonically increase with an increase in the intensity of the photospheric magnetic field, as might be expected from general considerations. At large magnetic fields (B > 140 mT), this dependence becomes inverse.

The results of the authors’ studies of acoustic-gravity waves (AGW) in the upper Earth’s atmosphere for recent years are presented. The work was generally aimed at the development of theoretical AGW models taking into account the real atmosphere properties and the verification of these models by spacecraft measurement data. The possibility of the existence of new evanescent acoustic-gravity wave types was theoretically shown; in particular, a previously unknown inelastic mode and a family of evanescent pseudo-modes were revealed. The possibility of observing evanescent modes on the Sun and in the Earth’s atmosphere was analyzed. The specific features of the propagation of acoustic-gravity waves at the interface between two isothermal half-spaces with different temperatures depending on their spectral parameters and the temperature jump magnitude at the interface were studied. The peculiarities of the interaction of acoustic-gravity waves with spatially inhomogeneous atmospheric flows were also investigated. The observed effects resulting from such interaction were analyzed to reveal the wave propagation azimuths, the change in their amplitudes, and the effect of blocking in the counterflow. The effect of vertical nonisothermicity on the propagation of acoustic-gravity waves, including the modification of acoustic and gravitational regions depending on the temperature, was studied. Based on the modified Navier-Stokes and heat-transfer equations, the effect of attenuation on the propagation of acoustic-gravity waves in the atmosphere was analyzed. The specific features of the viscous attenuation of different evanescent AGW types in the atmosphere were considered. The rotation of the atmosphere was shown to result in the modification of the continuous spectrum of evanescent AGWs with frequencies exceeding the Coriolis parameter.

Comprehensive simulation of a number of main processes induced in all geospheres by the fall and explosion of the Kyiv meteoroid on April 19, 2023, have been conducted. Magnetic, electrical, electromagnetic, ionospheric, and seismic effects and the effects of acoustic gravity waves have been assessed. The magnetic effect of the ionospheric currents and the current in the wake of the meteoroid could be considerably large (approximately 0.4–0.7 nT). Owing to the capture of electrons in the atmospheric gravity wave field, the magnetic effect can reach the levels of 0.6–6 nT. Under the influence of an external electric field, a transient current pulse with a current strength of up to approximately 10²–10³ A can arise. The electrostatic effect can be accompanied by the accumulation of an electric charge of approximately 1–6 mC, which produces the electric field strength of approximately 10 MV/m. The flow of the electric current in the meteoroid wake can give rise to generation of an electromagnetic pulse in the 10–100 kHz band with an electric field strength in the range of 1–10 V/m. The electromagnetic effect of infrasound could be substantial (approximately 0.6–6 V/m and approximately 2–20 nT). The absorption of the shock wave at the ionospheric dynamo region altitudes (approximately 100–150 km) can generate secondary atmospheric gravity waves with a relative amplitude of approximately 0.1%. The fall of the meteoroid produced a plasma wake not only in the lower atmosphere but also in the upper atmosphere at altitudes of not less than 1000 km. The possibility of the appearance of an electrophonic effect is unlikely. The possibilities of generating the ion and magnetic sound by infrasound and generating gradient drift and drift dissipative instabilities seem to be unlikely as well. The magnetic, electrical, and electromagnetic effects dealt with in this study partially fill up gaps in the theory of physical effects produced by meteoroids in the Earth–atmosphere–ionosphere–magnetosphere system. The magnitudes of magnetic, electrical, electromagnetic, ionospheric, and acoustic effects are significant. The magnitude of the earthquake caused by the meteoroid explosion did not exceed one. The mean rate of recurrence of the fall of celestial bodies similar to the Kyiv meteoroid equals 32.3 yr^–1, i.e., one event in 11 days.