Kinematics and Physics of Celestial Bodies最新文献

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.

During typhoon activity, the atmospheric gravity waves (AGWs) will cause the Earth’s ionosphere to fluctuate, causing the equivalent reflection height of the ionosphere to change, resulting in an abnormal change in the phase of the VLF signal received by the receiving station. Therefore, This paper analyses the response of phase the VLF signal to atmospheric gravity waves, using the VLF monitoring system to study the VLF signal data received by the Xinxiang receiving station during typhoon “Dan” in October 1999, which was transmitted from the Novosibirsk launching station of the Russian Alpha navigation system. Then the effect of the atmospheric gravity wave on the VLF signal propagation is studied based on the waveguide mode theory. It is calculated that when the frequency of the VLF signal is 14.9 kHz on 9 October 1999, the phase change is 5.12 cec, and the phase change on 12 and 13 October is 4.36cec and 3.34 cec respectively. Space weather conditions, and solar flare data released by the GOES satellite were then analyzed and their effect on the phase of the VLF signal was excluded. The results show that the phase anomaly of the VLF signal is caused by the atmospheric gravity wave excited by the typhoon. Therefore, the effect of atmospheric gravity waves on VLF signal propagation studied in this paper could predict and correct the phase of VLF signals, ensure the accuracy of the VLF navigation system as GPS backup, and have great significance for improving the accuracy of VLF navigation and positioning.

Ionospheric modelling is one of the most powerful tools for studying the behavior of the ionosphere. The aim of this paper is to assess the performance of IRI-Plas2017 in five different longitudinal sectors during different phases of solar cycle 24 (2011–2017). An hourly mean value of Total Electron Content (TEC) was used to study the diurnal and seasonal variations in TEC. An annual error plot profiled on monthly basis was used to study the difference between the measured and predicted TEC values. The annual TEC deviations were used to investigate the relationship between TEC derived from Global Positioning System (GPS) and IRI-Plas2017 model. Our results showed that the highest peak value of TEC was recorded as ~89 TECU (06:00UT) in the Asian sector (BAKO) while the lowest peak value of ~22 TECU (08:00UT) was recorded in the Australian sector (DAV1) in the ascending and descending phase during the March equinox respectively. Semi-Annual variation is a prevailing factor in all the solar cycle phases in the Africa and Asian sectors except during the descending and maximum phase where anomalies were recorded. Semi-annual anomalies were also prominent in all the solar cycle phases in the Australian, American, and Asian sectors. Winter anomaly was predominant in all the phases of solar cycle in the American, Asian, and European sectors. However, the IRI-Plas2017 model was not able to appropriately reproduce the two prominent phenomena (Semi-annual Variations and Winter Anomalies) observed in all the five longitudinal sectors.

This work analyzes the electromagnetic mechanism of interaction between subsystems in the Earth–atmosphere–ionosphere–magnetosphere (EAIM) system. The study is based on a system of equations for the volumetric density of electromagnetic energy and the total electron content of high-energy electrons in the magnetic flux tube, which describes the resonant interaction between waves and particles at the cyclotron frequency. The purpose of this work is to obtain analytical solutions to the system of equations describing the interaction of powerful electromagnetic radiation with high-energy magnetospheric electrons and to numerically model the main parameters of this interaction. Solutions for both the stationary and nonstationary problems have been obtained. Aperiodic and quasi-periodic modes of disturbances have been identified. The value of the stationary relative disturbance of total electron content, as a function of the particle and electromagnetic radiation source parameters, has been calculated. The dependence of various magnetospheric and ionospheric parameters on the electron and electromagnetic radiation source parameters has been determined. The radiation from a single lightning strike can lead to significant electron flux densities (~10⁵–10¹¹ m^–2 s^–1). In this case, the electron density in the ionosphere can increase from tens of percent to several hundred times. The disturbance of the geomagnetic and ionospheric electric fields, caused by ionization bursts in the ionosphere, has been calculated. The amplitude of geomagnetic field disturbances ranged from fractions to hundreds of nanoteslas, while the electric field disturbance varied from 10 μV to 100 mV. Secondary effects in the EAIM system, caused by the electromagnetic mechanism of disturbances, are briefly discussed.

The scientific and organizational activities of the prominent Ukrainian astrophysicist, planetary scientist, and academician of the Ukrainian SSR Mykola Pavlovych Barabashov are studied. The stages of the scientific path of the talented scientist, one of the founders of planetary science, who devoted his life to the study of the bodies of the Solar System, are highlighted. The ways of implementing well-known astronomical projects initiated and implemented by Academician Barabashov at Kharkiv State University in order to organize high-quality observations and improve the results obtained are analyzed. The contribution of Mykola Barabashov to the formation of planetary research in the astronomical institutions of the Soviet Union through the functioning of the Commission on Planetary Physics of the USSR Academy of Sciences, which he oversaw for many years, is considered. The photometric and, later, spectrophotometric and polarimetric studies of the Moon and planets initiated by Mykola Barabashov at the Kharkiv Astronomical Observatory led to the formation of a dynamically developing scientific school of planetary science. With the beginning of the space era in human history, the results of the activities of the representatives of the school received international recognition, as the study of solar system objects has acquired applied significance. The article characterizes the areas of works that were jointly carried out by the students and followers of Academician Mykola Barabashov at the Kharkiv Astronomical Observatory together with their scientific leader. The degree of involvement of Kharkiv astronomers under the general leadership of Mykola Barabashov in the projects of the Soviet space program in the early 1960s is determined.