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 Ωp = 77.7° and ip = 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.
According to classical magnetohydrodynamics, the magnetic fields on the Sun are characterized by huge theoretically calculated time intervals of their ohmic dissipation due to the high inductance caused by the large size of the fields and the high gas kinetic electrical conductivity of the plasma. This is in striking contrast to the observed rapid changes in the structure of solar magnetism. To solve such a contradiction, it becomes relevant to search for new methods of studying magnetized plasma. Research efforts to consider turbulent motions in the plasma ended with the creation of macroscopic magnetohydrodynamics (MHD), within which substantial decreases in the electrical conductivity and magnetic permeability leading to a decrease in the calculated time of reconstruction of global magnetic fields are found. This study aims at calculating the coefficients of turbulent electrical conductivity and turbulent magnetic permeability of the solar plasma and analyzing changes in the spatiotemporal evolution of the global magnetism of the Sun considering these parameters. Macroscopic MHD methods are used for studying the behavior of global electromagnetic fields and hydrodynamic motions in turbulent plasma. For models of the photosphere and convection zone of the Sun, the distributions of the following parameters along the solar radius are calculated: coefficients of kinematic (ν), magnetic (νm), and turbulent (νT) viscosities; hydrodynamic (Re) and magnetic (Rm) Reynolds numbers; gas kinetic (σ) and turbulent (σT) electrical conductivities; and turbulent magnetic permeability μT. The theoretically calculated parameters have the following values: ν = 0.2–10 cm2/s; νm = 6 × 108–8 × 102 cm2/s; νT = 1011–1013 cm2/s; Re = 5 × 1011–5 × 1013; Rm = 104–1010; σ = 1011–4 × 1016 CGS; σT = 109–4 × 1011 CGS; μT = 10–2–4 × 10–5. It is essential that σT ( ll ) σ and μT ( ll ) 1. Calculated turbulent magnetic diffusion DT = c2/4πσTμT turned out to be four to nine orders of magnitude higher than magnetic viscosity coefficient νm = c2/4πσ, which is responsible for the ohmic dissipation of magnetic fields. As a result, it becomes possible to theoretically explain the observed rapid reconstruction of magnetism on the Sun. We have revealed the radial inhomogeneity of turbulent viscosity νT and condition μT ( ll ) 1, which are indicative of the strong macroscopic diamagnetism of the solar plasma. In the lower part of the solar convection zone, the latter performs the role of negative magnetic buoyancy, thereby contributing to the for
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.
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.
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