Kinematics and Physics of Celestial Bodies最新文献

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.

A group of poorly studied eclipsing variables (the classification of which is marked as uncertain and/or the period of brightness changes is uncertain) has been studied with the using of the photometric observations of the TESS mission and NSVS, ASAS-SN sky-surveys. We also obtained some observations covering the brightness minima of our variables by our group using the telescopes at Astronomical Observatory on Kolonica Saddle (Slovakia) and Observatory and Planetarium in Hlohovec (Slovakia) during the “Variable-2024” astrocamp. The periods and classification were corrected. For NSV 575 and NSV 014 the periods were found for the first time, but it is doubtful that NSV 014 is an eclipsing variable, because there are no eclipses but the asymmetric wave is present, which indicates that the variable star can be re-classified as a low-amplitude pulsating one. Different methods were used for approximation of the light curves and further calculation of stellar system’s parameters such as eclipse depths and durations, values of reflection effect and effect of ellipticity of stars. The initial period was estimated using the periodogram based on the trigonometrical polynomial fit of high order (up to 10). For better approximation of the complete eclipsing phase curve, the “New Algol Variable” (NAV) software was used. The methods of “asymptotic parabolas” and “wall-supported asymptotic parabolas” were used for calculation of moments of eclipses, which use only near-eclipse part of the observations instead of a complete curve. These methods were implemented in the software MAVKA among a larger set of features. For the variables NSV 489 and NSV 1884, our moments of eclipses and the ones found in the literature, were used for the O–C curves. For NSV 489, the period was adjusted taking into account the slope of the (O–C) diagram.

The aim of this work is to analyze the impact of the kinetic temperature of electrons in a warm anisotropic plasma and the strength of its magnetic field on the integral characteristics of pulsar pulsed radio emission propagation, such as the dispersion measure (DM) and rotation measure (RM). An important aspect in this context is the presence of magnetic fields in the plasma, their strength, and their configuration relative to the line of sight. The approach uniquely accounts for polarization splitting into ordinary and extraordinary waves in pulsar pulsed radio emission and considers the limiting cases of quasi-longitudinal and quasi-transverse propagation of these waves in a medium with magnetic fields of various strengths, with or without scattering. This makes it possible to predict a possible dependence of the DM and RM on frequency (not previously anticipated), magnetic field strength, and electron kinetic temperature as well as the amplification of this dependence with increasing magnetic field strength. Notably, the frequency dependence of the DM and RM is more pronounced at low frequencies, with both measures increasing as frequency decreases. Accounting for these dependences when analyzing DM and RM toward different pulsars makes it possible to estimate cosmic magnetoactive plasma parameters, including the range of electron kinetic temperatures and the strengths of longitudinal and transverse magnetic field components along the path of polarized radiation propagation. Thus, using pulsar pulses as probing radio emission makes it possible to study warm magnetoactive plasma with magnetic field strengths of the order of 1–10 G or higher, such as the solar corona, the Jupiter–Io flux tube, and the Earth’s ionosphere.

The paper presents metrological parameters of the full-frame camera Canon EOS 6D Mark II’s photosensor. The working range of output signal levels is from 0.1 to 15 870 reference units DN. Depending on ISO parameter value, the sensor solarization takes place when the output signal reaches levels from 11 318 up to 15 870 DN. According to the data of laboratory experiments, it is shown that the range of the photosensor output signal in the area of its linear response to changes in the active light flux is 20.2–20.4 dB (ΔS is 107.3–11 595.6, 142.0–14 819.9, and 132.2–14 309.0 DN in R, G, and B channels of the sensor, respectively.) When using the logarithmic function of photosensor sensitivity, the range of its linear response increases to 38.2 dB (ΔS = 2.24–14 819.9 DN). The sensor’s local response in the R, G, and B channels to changes in active light flux is 558.63, 1164.0, and 691.37 DN/s at ISO 100; 1283.5, 955.29, and 206.9 DN/s at ISO 12 800; and 4263.6, 3119.2, 698.42 DN/s at ISO 40 000, respectively. The dependence of the sensor output signal level on the ISO value at an exposure time of T_exp = 5.2 s remains linear within the entire range of ISO values from ISO 100 to ISO 102 400 in all spectral channels of the sensor when using a logarithmic dependence log Se(log ISO). In the case when the sensor transfer function is presented on natural numbers scale, the sensor linear response ranges in R, G, and B spectral channels differ and are ΔISO_R,G,B = 1600–102 400, 2016–102 400, 3200–102 400 DN, respectively. In the highest informativeness areas of the linear sensor response ranges, the signal-to-noise ratio (SNR) of the output signal takes values from 5.0 dB to 34.5 dB (Rose’s criterion); accordingly, the signal increases from 4.5 to 12 560 DN and is controlled by the ISO level. Similarly, when the signal intensity depends on exposure duration, at ISO 100 within the sensor linear response ranges, the critical SNR values of output signals are 5.0 dB at S_av = 14.0 DN and 47.6 dB at S_av = 14 820 DN. At ISO 40 000, the SNR parameter takes values from 5.0 dB to 33.6 dB at signal levels of 160–230 and 13 522 DN, respectively. Taking into account the results of conducted analysis, the use of digital cameras with a CMOS sensor in photometric studies can be considered acceptable.

The aim of the paper is to assess the energy parameters of physical processes starting from the solar storm of April 21, 2023, and ending with the perturbations of the Earth’s lithosphere on April 23–24, 2023. The energy of processes in all subsystems of the Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere–lithosphere system is analyzed. A comparative analysis of this storm with an extreme storm is performed. The storm of April 23–24, 2023, was unique due to the shift of the auroral zone to the midlatitudes to 50°. The international auroral brightness scale is improved. The auroral energy scale is proposed.

The results of observations of small-scale variations in the hydrogen Balmer lines in the atmosphere of Vega are presented. The spectral observations are performed with a low-resolution spectrograph (R ~ 600) installed in the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. The spectra are obtained with a second-order time resolution. Variability has been detected in the hydrogen lines H_β, H_γ, H_δ, which can be interpreted as nonradial pulsations. The characteristic time of the observed variations ranges from 300 to 1200 s. The horizontal scale of the oscillating elements is approximately 800 mm, which is comparable to the solar radius. The radial velocity of the variations is approximately 36 km/s.

Due to the inclination of Saturn’s equator to the plane of its orbit at an angle of close to 27° and due to the presence of rings that block the arrival of solar radiation to the winter hemisphere for a long time, the planet’s atmosphere undergoes significant seasonal changes. Once every 14.7 Earth years, the planet’s rings are visible edge-on to an Earth-based observer, and then the insolation conditions for both hemispheres become the same. The most favorable opportunities for such observations were in 1966, 1980, 1995, 2009–2010, and 2024. The available observational data and the results of the authors’ calculations within the framework of a two-layer model of Saturn’s atmosphere for such equinoxes were compared. They showed that the latitudinal belts of the planet, which have just emerged from the shadow of the rings, usually differ significantly from other belts in their physical characteristics under practically the same physical and orbital conditions of the planet. From the analysis of the parameter values calculated for different latitudes, the conclusion was confirmed that, for the hemisphere that until the time of receiving observational data was shielded by rings (until 1966, 1995, and 2024 in the Southern Hemisphere and until 1980 and 2009 in the Northern Hemisphere), the cloud layer is more sparse and its upper boundary is at a higher altitude than in the hemisphere that “survived” the “summer” season before. Those equatorial regions of Saturn that were closed by rings for a long time, experiencing a deficit of solar radiation inflow into the atmosphere, differ from other latitude zones in an increased amount of some strongly absorbing color impurity. However, 2009 and, partly, 1995 do not correspond to this assumption. The northern equatorial region, which had just emerged from the shadow of the rings in 2009, did not show a significant decrease in methane absorption. That is, neither high-altitude haze nor a rarefied layer of clouds formed in this part of the atmosphere. Since, as a rule, these new formations are of a photochemical nature, it can be assumed that there was not enough energy for some reason in the atmosphere to form a photochemical aerosol layer, which usually formed in the lower stratosphere (upper troposphere) of Saturn, and which reduced methane absorption and increased albedo. The reason for this could be that the equinoxes on Saturn in 1995–1996 and in 2009–2010 occurred at times close to the minimum of activity on the Sun, when the solar activity index R differed only slightly from the zero value.