Kinematics and Physics of Celestial Bodies最新文献

The present work is carried out in order to analyze the data for more than 15 000 coronal mass ejections (CMEs) during solar cycle 24, spanning the period of 2009–2017. We investigated, the properties of two categories of CMEs, narrow (W ≤ 20°) and normal (W > 20°), including angular width, linear speed, acceleration and their location. Based on statistical analysis, it is found the following. (1) 45% of the CMEs found in the angular range of W ∼ 10° and 30° with peak at 15°. (2) 70% of the narrow and 60% normal CMEs speed lies in the range of 150–400 km/s. The occurrence rate of both categories of CMEs declines sharply at linear speeds > 400 km/s and 0.1% narrow while 1.95% are of normal category, having the speeds above than 1000 km/s. (3) The 99% of narrow and 82% of normal CMEs are biased towards deceleration whereas small portion of normal CMEs do move with positive acceleration. We observed a low correlation between linear speed and acceleration –0.13 and –0.24 for narrow and normal CMEs respectively. (4) The latitudinal distribution of almost all narrow and normal CMEs were observed from equatorial regions during solar minimum, while during solar maximum, the distribution becomes wider and appears at all latitudes for both catagories. Despite of the fact that, solar cycle 24 is a weaker one in terms of geoeffectivity, but we observe a greater number of CMEs than solar cycle 23 throughout the solar maximum.

Ionospheric effects of powerful seismic events are studied using total electron content (TEC) maps of the ionosphere (http://www.aiub.unibe.ch/download/CODE/) for the northern hemisphere, with the exception of the polar region, in the winter seasons of 2012–2018. It is shown that seismic ionospheric effect is a global effect superimposed by local effects above epicenters of individual earthquakes (EQs). Temporal TEC variations at the time of strong EQs at a large distance from their epicenters (global effect) consist of the two maxima: a precursor maximum and an aftershock maximum. Only a precursor maximum is usually recorded in TEC variations over the EQ epicenter (local effect), the amplitude of which at night (on average 8%) is about twice as high as that observed during day. The reduced amplitude values are observed always (locally and globally) for several days after a positive surge in TEC. The region of the maximum amplitude of the seismic ionospheric effect belongs to the middle latitudes, especially the range of 35° N–40° N latitudes, and, within this range, at longitudes near 30° W (Mid-Atlantic ridge) and 140° E–150° E (Japanese islands and adjacent waters of the Pacific Ocean). Latitudinal amplitude maxima of the seismic ionospheric effect agree well with the latitudinal maxima of the number of EQs in both geographic and geomagnetic coordinate systems. Changes in the number of EQs and, consequently, the ionospheric effect on geomagnetic coordinates are more organized, which is indicative of a substantial impact on seismicity of the same processes at the boundary of the liquid core and lower mantle that form the Earth’s magnetic field. In addition to seismic belts and zones of midocean ridges, an increase in TEC has been recorded along the so-called “lineaments” that mark the weakened zones of the Earth’s crust with increased flows of deep gases. The correspondence between the spatial features of seismicity and the seismic ionospheric effect gives evidence in favor of the radon mechanism of lithosphere–ionosphere coupling and indirectly confirms the role of deep gases in the formation of planetary features of seismicity.

The mechanism of electrical interaction between subsystems in the Earth–atmosphere–ionosphere–magnetosphere system is currently the least studied and substantiated subject. Moreover, some experts doubt its existence. This study is devoted to investigating the mechanisms of generation and propagation of electric fields that vary in time under the influence of transient high-energy sources of various physical nature and atmospheric turbulence enhanced by these sources, which is an urgent problem. Four options of penetration of electric fields from the atmospheric surface layer into the ionosphere have been proposed. Electrical parameters that depend on disturbances in the electric charge density and the characteristics of atmospheric turbulence have been estimated and numerically calculated for a number of high-energy sources. It is shown that the disturbances arising in the atmospheric surface layer are capable of penetrating into the ionosphere and even into the magnetosphere.

We study a system of equations, involving a large parameter, arising from the study of stellar pulsation for which a combination of procedures is used to approximate a fun damental solution. We present a combination of singular and non-singular perturbation methods which, aided by symbolic computation, may be of multi-disciplinary interest for the analysis as well as a astrophysics application. Example software is presented in the Wolfram Language (Mathematica version 13.2).

Statistical dependences of orbit parameters in four groups of sungrazing comets are studied. It is shown that the perihelia of comets of the Kreutz family are clustered around two planes (great circles of the celestial sphere). Numerical data on the observed bifurcation of perihelion distribution are provided. One of the planes basically coincides with the plane obtained by averaging orbit parameters Ω and i. The second plane with parameters Ω_p = 77.7° and i_p = 266.1° has an inclination of approximately 64° relative to the first plane. The distant nodes of cometary orbits relative to this plane are clustered at a distance of approximately 2 a.u. On the basis of the above, one of the authors hypothesizes that the comet group originates from the collision of a large comet with a meteoroid stream. This study examines some counterarguments expressed regarding this hypothesis. It is shown, based on a particular case, that the assumptions about the concentration of comet perihelia near one point and along two circles of the celestial sphere are quite compatible. The distribution of orbit inclinations relative to this plane is analyzed and a sharp maximum near 90° is noted. The maximum indicates that the parent body experienced lateral impacts of meteoroid bodies in all probability, which caused defragmentation of the former. New confirmations of the suggested hypothesis about the presence of another group of sungrazers have been found. It is assumed that the correlation dependence between the values of the perihelion parameters and ascending nodes of cometary orbits is of an evolutionary nature and is related to the group formation process. New relationships that concern the Meyer, Kracht, and Marsden groups are introduced. In particular, the authors have calculated the planes near which the cometary perihelia of these groups are concentrated. The example of the Meyer group illustrates the bifurcation of perihelia.

The theoretical and experimental study of the geomagnetic effect of cosmic bodies remains an urgent problem. This is especially true for meter-sized meteoroids, for which the very existence of the magnetic effect remains in question. The purpose of this article is to present the results of the analysis of temporal variations of the X-, Y-, and Z-components of the geomagnetic field detected by the International Real-time Magnetic Observatory Network (INTERMAGNET) on the day of the Kyiv meteoroid fall and on reference days. The analysis of temporal variations has shown that the levels of these components on the day of the cosmic body explosion and on reference days were significantly different. The level of X-component with a 6 min delay decreased by 2…5 nT, which lasted approximately 60 min. With a delay of 25 min and a duration of 25 min, a quasi-periodic disturbance was observed with a variable period within 4…12 min and an amplitude increasing from 0.3…0.4 to 1.2…1.5 nT. The first disturbance, which had a speed of approximately 300 m/s, could have been caused by a blast wave. The second disturbance was most likely associated with the generation and oblique propagation of an atmospheric gravity wave with a speed of hundreds of meters per second. Within the ionosphere, the disturbance propagated at a speed of approximately 660 km/s by means of magnetohydrodynamic waves. The temporal variations of the Y- and Z-components on the day of the explosion fluctuated for 60 min and decreased by 5…10 nT. The mechanism of long-lasting disturbances of these components remains unknown. It is likely that it could be related to the diamagnetic effect. There are reasons to believe that meter-sized cosmic bodies can cause the detected magnetic effect.

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.