Kinematics and Physics of Celestial Bodies最新文献

The main goal of the study is to search for super-strong magnetic fields in “quiet” sunspots without flares. The authors’ method is based on Stokes V spectropolarimetry in a wide spectral range, from –5 to +2.5 nm relative to the D₃ He I line. The objects of the study are two simple sunspots with diameters of 35–40 Mm, observed on 17 and 24 July, 2023, near the center of the solar disk, at heliocentric angles of approximately 18°. Novelty of the study consists in the fact that characteristic spectral features are detected in the second sunspot at distances of approximately –1.88 and –0.84 nm from the D₃ He I line, which can be strongly split sigma-components in the Zeeman effect of the mentioned line for the following principal reasons: (a) their Stokes V signs are opposite, and the amplitudes reach 5%, which significantly exceeds the measurement errors, (b) the amplitudes of the blue and red peaks vary synchronously in different places of the sunspot, and (c) the spectral profiles of both peaks have similar shapes and are mutually antisymmetric. If the indicated spectral features are interpreted as a manifestation of the combined action of the Zeeman and Doppler effects, then one can assume the presence of very fine-structured (spatially unresolved) jets in the sunspot that have a magnetic field on the order of 10⁵ G and a plasma ascent speed at the level of 700 km/s. Within this interpretation, it becomes possible to address two current problems in heliophysics: the anomalously rapid rotation of the corona at low latitudes and the occurrence of super-strong magnetic fields at chromospheric and coronal levels.

The influence of turbulent mixing on the vertical profile of electric-field intensity in the atmospheric boundary layer is investigated. The effects of meteorological conditions and thermodynamic stratification on the electrical conductivity and structure of the electric field are analyzed. It is shown that the turbulent diffusion coefficient K(z), which determines the vertical transport of electric charge, can vary significantly with altitude depending on atmospheric stratification. Several models for describing K(z) are considered, including empirical and theoretically grounded approaches (the Monin–Obukhov model). Calculations based on radiosonde data from the Norderney station (WMO 10 113) for the winter and summer seasons have made it possible to trace seasonal differences in the distributions of the turbulent diffusion coefficient and electric-field intensity. Additionally, data from station 2TDJJ8J aboard the research vessel Polarstern RV, which operates near the Earth’s poles during polar summer, are analyzed. This makes it possible to compare changes in the electric field and the turbulent diffusion coefficient for high-latitude regions of both hemispheres. The similarity of exponential field decay with altitude is established, and differences indicating regional characteristics of atmospheric stratification are identified.

Solar eclipses (SEs) are accompanied by both regular and a number of irregular effects as well as individual effects inherent in a particular SE. The following questions remain unanswered: can there be effects prior to an SE? How long do they last after the end of an SE? Do they appear on the night side of the planet? What effects occur in the magnetically conjugate region? What is the role of dynamic processes and geophysical fields in the interaction of subsystems in the Earth–atmosphere–ionosphere–magnetosphere system during an SE? These questions need to be addressed. The aim of this paper is to present the results of observations of temporal variations of total electron content (TEC) in the ionosphere over China obtained using Global Navigation Satellite System during the SE and reference days. The low-latitude ionosphere has certain features that could not fail to manifest themselves in the effects of the SE. Estimation of the ionospheric response to the annular SE was performed using recordings of GPS satellite signals obtained on dual-frequency receivers. The error of the TEC calculation technique used in the study does not exceed 0.1 TECU. To obtain acceptable results, the mutual motions of the TEC measurement point, lunar shadow, and Earth’s rotation were taken into account. The ionospheric effect of the SE, which consisted in a significant reduction in TEC, was confidently observed at all five stations and for all seven satellites. It was found that the deficit of TEC clearly followed the maximum magnitude value of the SE. The maximum TEC depletion reached 6–7 TECU at a magnitude of M_max ≈ 0.976–0.986. In this case, the relative TEC depletion was 35–37%. The time delay of the maximum reduction in TEC relative to the maximum magnitude of the SE was close to 15 min. This result is in good agreement with the known data. The moments of the beginning and end of the TEC depletion, in general, did not coincide with the changes in the SE magnitude. The duration of the ionospheric effect was usually longer than the duration of the eclipse. There was no clear dependence of the ionospheric effect on latitude and longitude. No increase in the wave activity during the SE was detected. The effects of the annular SE, which took place in the low-latitude ionosphere near the summer solstice, had a number of features.

Modern experimental and theoretical studies of atmospheric gravity waves (AGW) indicate the need for a nonlinear consideration of these processes. First of all, this is due to the exponential growth of the amplitudes of gravity waves with height in the atmosphere, which significantly limits the possibility of applying the linear theory. In the work, analytical solutions of the system of nonlinear equations describing the propagation of atmospheric gravity waves in the isothermal atmosphere were obtained. To find the solutions, nonlinear equations obtained earlier in the model of two-dimensional motion of an ideal atmospheric gas in the Boussinesq approximation were used. The nonlinear components in these equations have the form of Poisson brackets. We found the solutions of the nonlinear equations in the form of plane waves. For this type of solution, the Poisson brackets are converted to zero. This approach allowed us to obtain analytical solutions that describe various types of nonlinear gravity waves in an isothermal atmosphere. In the linear theory of AGW, solutions in the form of plane waves are in the assumption of small amplitudes of perturbations. Unlike the linear consideration, the solutions of the nonlinear equations that were obtained do not have restrictions on the amplitude. Within the framework of the specified simplifying assumptions, solutions were obtained from the system of nonlinear equations for: (1) freely propagating internal gravity waves, (2) horizontal (evanescent) atmospheric gravity waves, and (3) important special cases of evanescent wave modes. The energy conditions for the realization of the obtained types of wave perturbations in an isothermal atmosphere were analyzed. The specified nonlinear solutions (1)–(3) are nondivergent since a system of nonlinear equations was used when obtaining them, written in the assumption of zero velocity divergence. At the same time, in the linear theory, the assumption of zero velocity divergence singles out only one f-mode from the entire AGW spectrum. That is, the application of nonlinear theory when considering gravity waves, even with significant simplifications in the original system of nonlinear equations, significantly expands the class of wave solutions in comparison with the linear theory.

This study presents a detailed analysis of five cataclysmic variable systems of the dwarf nova class: Gaia21djh, Gaia19bwr, Gaia21akq, Gaia21enu, and Gaia18cjn. Using photometric data from the TESS space telescope and the ASAS-SN sky survey archive, the superhump periods (P_sh) and orbital periods (P_orb) for three SU UMa-type systems were determined. For Gaia21djh, P_sh = 0.08214 days and P_orb = 0.0786 days were obtained; similar values were determined for Gaia19bwr and Gaia21akq. For Gaia18cjn and Gaia21enu, the presence of stable superhumps was not confirmed, although Gaia18cjn shows an orbital period of P_orb = 0.189 days. The analysis of physical parameters, including mass ratios q, component masses M₁ and M₂ and radii R₁ and R₂ showed that all SU UMa systems have low q values (<0.3) consistent with tidal instability. For example, Gaia21akq has q = 0.24 ± 0.03, which supports previous theoretical models. The study of superoutburst parameters revealed significant variability in the duration of different phases. Gaia19bwr exhibited the longest plateau phase duration (D_P = 9.6 ± 1.7 days), while it was D_P = 6.5 ± 0.6 days for Gaia21akq. The largest superoutburst amplitudes were observed in Gaia21djh (A_SO = 4.3 ± 0.2) and Gaia19bwr (4.2 ± 0.3). The obtained results are consistent with the thermal-tidal instability model for SU UMa-type systems and highlight the importance of high-precision photometric observations in studying accretion disk dynamics.

The authors analyze the long-term changes in the reflective properties of Jupiter’s atmosphere in order to study seasonal variations and the influence of solar activity. Jupiter has a very dynamic atmosphere consisting primarily of hydrogen and helium. Trace amounts of ammonia, methane, and other compounds form the visible cloud layers and haze above the clouds. The planet’s powerful magnetosphere plays an important role in the formation of the observed phenomena. The significant eccentricity of Jupiter’s orbit (e ≈ 0.0485) causes the solar energy input to the planet’s atmosphere to vary by 21% between perihelion and aphelion. The Northern Hemisphere receives significantly more energy because its summer solstice occurs during the planet’s passage through perihelion. This causes variations in the physical characteristics of the atmosphere and indicates the presence of seasonal changes. In order to quantify these changes, the brightness ratio of the northern and southern tropical and temperate regions A_J = B_N/B_S as a factor of photometric activity of atmospheric processes were used. Analysis of these data for the period 1960–2025 has revealed a clear periodicity in A_J changes with a period of approximately 11.87 years, which corresponds to Jupiter’s orbital period and indicates seasonal atmospheric restructuring processes. The effects of orbital eccentricity (a 21% variation in insolation) and solar activity (notably the 22-year Hale cycle and UV radiation) on Jupiter’s various atmospheric layers are analyzed. The characteristic radiative relaxation time of Jupiter’s atmosphere is found to be approximately 3.4 years (τ_R ≈ 1.07 × 10⁸ s) during intervals of coordinated orbital and solar forcings. A phase of imbalance from 1995 to 2012 and its subsequent recovery have been documented, accompanied by a decrease in the effective radiative constant to approximately 2.5 years (τ_R ≈ 0.79 × 10⁸ s), likely reflecting an enhanced influence of solar activity on the upper atmosphere.

Powerful transient processes on the Sun lead to solar storms and to geospace storms on Earth. Ionospheric storms are an integral part of geospace storms; they are extreme manifestations of ionospheric weather. Its variations have a significant impact on the functioning of civilization. It has been established that the manifestations of storms significantly depend not only on the characteristics of solar and geospace storms but also on the season, time of day, magnetic and geographical coordinates, etc. All this determines the relevance of studying each new ionospheric storm, especially when it comes to unique events. The purpose of this work is to study the features of the global manifestation of a unique geospace storm on May 10–13, 2024, in the F region of the ionosphere. The main features of the global manifestation of a unique geospace storm on May 10–13, 2024, in the F region of the ionosphere have been studied. The largest negative disturbances were observed on May 11, 2024, during the recovery phase of the geomagnetic storm. At most stations, the storm was strong or severe during the daytime. At night, manifestations of strong, severe, and extreme storms were mainly observed. The storm of May 13, 2024, was less intense compared to the storm of May 11, 2024. During the daytime, it was minor and moderate, while it was mainly strong and even severe at night. Negative and positive ionospheric storms sometimes replaced each other. Positive ionospheric storms were weaker. The duration of the blackout tended to decrease with decreasing geographical latitude of the station.

This article presents the results of observations and data processing of the occultation of star TYC 1318-01031-1 by asteroid (52) Europa conducted at multiple sites. Data from both professional astronomers and experienced amateur observers are utilized. Professional observations have been conducted with an 80-cm diameter telescope equipped with a QHY174M GPS camera, which provides precise UTC time-stamping for each exposure via its integrated GPS receiver. Amateur observations have been carried out with various telescopes and cameras, with the data recorded in video format. The video recordings were processed using a unified methodology to derive the photometric occultation light curve. Ingress and egress times of the occultation at each observing site are determined from the extracted photometric light curves of TYC 1318-01031-1. A proprietary method is applied to combine occultation chords from geographically dispersed sites where observations have been acquired independently [1]. Subsequent processing employs the proposed combination method to compute each site’s offset from the occultation path centerline. Chords of asteroid (52) Europa for each observing site are then calculated from the measured ingress and egress times of the occultation. Calculated asteroid chords are compared to the 3D shape model of the asteroid from the Database of Asteroid Models from Inversion Techniques (DAMIT). This approach yields strong validation of the technique and demonstrates that amateur observations, taking into account potential UTC time-stamping errors, can be used to reconstruct asteroid shapes. The results also confirm that the shape and dimensions of asteroid (52) Europa in the DAMIT database are accurate.

The black hole entropy problem, often framed through the semi-classical relation between horizon area and entropy, challenges the consistency of quantum gravity and thermodynamic principles. Within the framework of string theory, Fuzzball solutions offer a nontrivial resolution by positing that black holes are ensembles of horizonless microstates, whose degeneracy matches the leading-order entropy scaling predicted by S ~ A. This paper conducts a comparative analysis of Fuzzball microstate geometries against other competing proposals, such as holographic dualities, where S_CFT asymptotically approaches black hole entropy and approaches derived from loop quantum gravity, which quantize spacetime at the Planck scale. Recent advancements in the moduli space of supersymmetric and near-extremal Fuzzball solutions have pushed forward our understanding of microstate counting, though extending these solutions to nonextremal configurations remains a formidable challenge. Moreover, the emergence of Hawking radiation as a coherent quantum process, while preserving unitarity, raises new questions about the completeness of the Fuzzball paradigm in resolving the information paradox. In this work, we explore the complex interplay between gravitational entropy, quantum information, and the non-local structure of spacetime, ultimately confronting the limitations and future directions of Fuzzball theory in addressing the full range of gravitational entropy phenomena.

The quantitative analysis of processes in the subsystems electric field–ionospheric current–atmosphere–ionosphere and electric field–atmosphere–lithosphere, triggered by powerful geomagnetic storms, is a relevant task. The study aims to assess the impact of the electrical storms of magnetospheric-ionospheric origin on the interaction between the external and internal geospheres. The study quantitatively evaluates the role of such electrical storms in the interaction between the external and internal geospheres within the SIMMIAE system. Due to the dissipation of ionospheric current under the action of the electric field, the atmospheric temperature at altitudes of 120–350 km increases by tens to hundreds of Kelvins during the day and by units to hundreds of Kelvins during the night. It has been shown that the heated atmospheric gas rises with a speed varying from tens to hundreds of meters per second depending on altitude. The characteristic time for the ascent of heated atmospheric gas decreases with altitude, from approximately 10 to 4 min during the day and from 40 to 8–9 min during the night. The heat flux density is maximal at an altitude of around 150 km, reaching 20 mW/m² during the day and 0.1–0.2 mW/m² during the night. The maximum power of Joule heating in the atmosphere is 200 GW during the day and 1–2 GW during the night. The quantity of Joule heat in the atmosphere reaches 200 TJ during the day and 5–6 TJ during the night. An electrical storm of magnetospheric-ionospheric origin also induces an electrical storm in the lithosphere. In this case, the electric field strength in the lithosphere can reach approximately 10–100 µV/m, the power of Joule heating ranges from 1 to 1000 MW, and the energy spans 1–40 000 GJ. Joule heating of the atmosphere and lithosphere acts as a triggering process in response to the electric field. The triggering coefficient ranges from 10¹⁰ to 10¹¹ for the thermosphere and from 10¹² to 10¹³ for the lithosphere. Seven-point scales for classifying electrical storms in the atmosphere and lithosphere are proposed.