Kinematics and Physics of Celestial Bodies最新文献

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.

From May 17, 2020 to November 26, 2022 (GPS weeks 2106–2237) all products of the International GNSS Service (IGS)—precise ephemerides of GPS and GLONASS satellites, coordinates and velocities of permanent GNSS stations, etc.—were based on the IGb14 reference frame, the second IGS realization of the release of the International Terrestrial Reference Frame ITRF2014. Observations of GNSS satellites at permanent stations located in Ukraine and in Eastern Europe for this period were processed in the GNSS Data Analysis Centre of the Main Astronomical Observatory (MAO) NAS of Ukraine. The processing was carried out with the Bernese GNSS Software ver. 5.2 according to the requirements of the EUREF Permanent GNSS Network (EPN), that were relevant at that time. In total, observations on 344 GNSS stations, including 273 Ukrainian stations belonging to the following operators of GNSS networks: MAO NAS of Ukraine, StateGeoCadastre of Ukraine (UPN GNSS), PJSC System Solutions (System.NET), NU Lviv Polytechnic (GeoTerrace), Navigation and Geodetic Center (NGC.net), Kiev Institute of Land Relations (KyivPOS), Coordinate navigation maintenance system of Ukraine (NET.Spacecenter), E.P.S. LLC, UA–EUPOS/ZAKPOS, TNT TPI company (RTKHUB Network), and KMC LLC, were processed. The IGb14 reference frame was set by No-Net-Translation conditions on the coordinates of the EPN Class A stations from the EPN C2130 catalogue. As result, the station coordinates in the IGb14 reference frame and the zenith tropospheric delays for all stations were estimated. The mean repeatabilities for components of station coordinates for all weeks (the characteristics of the precision of the received daily and weekly solutions) are in the following ranges: for north component—from 0.62 to 1.35 mm (the average value is 0.98 mm), for east component—from 0.73 to 1.45 mm (the average value is 1.09 mm) with outliers of 2.39 and 1.81 mm for GPS weeks 2159 and 2168 respectively, for height component—from 2.52  to 6.36 mm (the average value is 3.89 mm).

Inertia is one of the most vivid and at the same time puzzling physical properties of bodies. As an equivalence between inertial and gravitational mass in general relativity, there is still no experimentally confirmed quantum mechanical description of inertia. There is great hope for such a description, as it could possibly elucidate cosmological anomalies and provide the missing link between relativistic theories and quantum mechanics. In this work, we refute the explanation of inertia by the concept of Modification of inertia resulting from a Hubble-scale Casimir effect (MiHsC) or Quantized Inertia (QI).

Comprehensive modeling studies of the thermal, turbulent, and plasma processes induced in all geospheres by the passage and explosion of the Kyiv meteoroid on April 19, 2023, were performed. Thermodynamic and plasma effects, as well as the effects and turbulence, accompanying the passage of the Kyiv meteoroid were estimated. It has been shown that the passage of the celestial body led to the formation of a gas-dust plume. The heated trail of the meteoroid cooled for several seconds. A simplified one-dimensional model of plume motion in the vertical direction is considered. The acceleration and speed of the plume are estimated. It has been shown that the initial acceleration of the plume initially reached a maximum value of 117 m/s² and lasted ~1 ms. Its speed increased from 0 to ~1 m/s, then gradually decreased to 0 m/s. At this speed, the height of the plume’s ascent hardly increased. The products of the explosion contained in the thermal, specks of dust and aerosols, further took part in the following three processes: a slow precipitation to the surface of the Earth, turbulent mixing with the ambient air, and transport by the predominant winds around the globe. The effect of turbulence in the trail has been shown to be well-pronounced, while the effect of magnetic turbulence has been shown to be absent. The following basic parameters of the plasma in the trail have been estimated: the height dependences of the electron densities per unit length and per unit volume, their relaxation times, the particle collision frequencies, the plasma specific conductivities, and the electron temperature relaxation time. At the initial moment, the linear and volume electron densities in the trail have been shown to be equal to approximately 10¹⁷–10²³ and 10¹⁷–10²² m^–3, respectively, and the plasma specific conductivity to be equal to ~10³ Ohm^–1 m^–1. The role of the dusty plasma component was insignificant.

The influence of the Earth’s rotation on the spectrum of low-frequency wave disturbances in an isothermal atmosphere is investigated. The system of equations for small linear disturbances is obtained in the “traditional” approximation and in the β-plane approximation, taking into account the frequency of rotation of the atmosphere. The found equations differ from the previously obtained ones in that the left parts of the equations depend only on time, whereas the right parts are expressed in terms of disturbed pressure. It is shown that, at zero perturbed pressure, taking into account the atmospheric rotation in the equations leads to the “splitting” of the obtained system into separate equations describing vertical and horizontal perturbations. Compact analytical solutions were obtained for both types of disturbances. It was established that vertical disturbances are realized in the form of Brunt–Väisälä waves, while horizontal are realized in the form of Rossby waves and inertial oscillations.

In this paper, we have investigated the effect of small perturbations in the Coriolis (ϕ) and centrifugal (ψ) forces in the Photogravitational magnetic binary problem including the effect of third body as variable mass. The objective of this work is to analyse the effect of ψ and other parameters (magnetic moments (λ) and radiation pressure (q)) on the existence and evolution of equilibrium points, basins of convergence (BoC), degree of unpredictability in BoC. In addition, to examine the effect of ϕ and ψ (in the presence of other parameters) on the stability of equilibrium points are also one of the aspect of this work. For different values of parameters, a total number of cases of non-collinear equilibrium points are 3, 5 and 7. The effect of various parameters on the evolution of equilibrium points are explained with the help of graphs. All non-collinear equilibrium points are found to be unstable for permissible range of parameters present in this model. The change in geometry of BoC’s is also shown and explained using graphs. The effect of ψ, q and λ on the degree of unpredictability in BoC’s is examined using the method of basin entropy. It is found that for the complete range of λ and q, the BoC’s are in fractal region. Also, for the values of ψ = 1.37, 1.38 and 1.40 to 1.44, the boundaries of BoC’s are in non-fractal region.

An actual problem today is the search for observed evidence of the existence of deep small-scale magnetic fields of the Sun. In this regard, the authors analyzed the theoretical criterion for separating the contributions to the solar surface magnetism of two qualitatively different mechanisms of a small-scale dynamo, the action of which is hidden in the depths of the solar convection zone (SCZ), proposed by Sokoloff and Khlystova [Astron. Nachr. 2010. 331. P. 82–87]. The first mechanism ensures the generation of small-scale magnetic fields due to the interaction of turbulent motions with the mean magnetic field (small-scale dynamo-1 of macroscopic MHD), while the second mechanism causes self-excitation of magnetic fluctuations due to turbulent pulsations of highly conductive plasma ( diffusive small-scale dynamo-2 of classical MHD). The essence of the proposed criterion is that deep small-scale magnetic fields can lead under certain conditions to violations of Hale’s and Joy’s laws of observed magnetism on the surface of the Sun. Statistical analysis of these disturbances allows one to identify the differences in the evolution of the observed manifestations of two sources of small-scale fields since the contribution of two deep dynamo mechanisms to surface magnetism varies with the phase of the solar cycle in different ways. Such an important feature is the behavior of the percentage of anti-Hail groups of sunspots (in relation to the total number of sunspots) during the cycles. In the case of small-scale dynamo-1, the percentage of anti-Hale groups is independent of cycle phase, whereas the percentage of anti-Hale groups associated with diffusive small-scale dynamo-2 should reach its maximum value at solar minima. Therefore, the variations of magnetic anomalies make it possible to separate the meager contributions of two small-scale dynamo mechanisms to surface magnetism. In this connection, the task of identifying the markers of a small-scale dynamo in the solar depths from observations becomes relevant. With this in mind, we conducted an analysis of literature data of statistical studies of long series of observed violations of Hale’s and Joy’s laws, which can be caused by the presence of deep small-scale magnetic fluctuations of various origins. In particular, it was demonstrated in the work of Sokoloff, Khlystova, and Abramenko [Mon. Notic. Roy. Astron. Soc. 2015. 451. P. 1522–1527] on the basis of processing the data of different catalogs for the period 1917–2004 that the percentage of anti-Hale groups of spots increases during the minima of solar cycles. This testifies to the operation of a diffusive small-scale turbulent dynamo-2 within the SCZ, the efficiency of which becomes noticeable near the minima of the cycles, when the global toroidal magnetic field weakens. As a result of the authors' analysis of six magnetic active regions observed near the minima of the 24th and 25th solar cycles, characteristic violations of Hale’s and Joy’