Volume 32, Issue 1

In this follow-up article, we investigate the use of convolutional neural network for deriving stellar parameters from observed spectra. Using hyperparameters determined previously, we have constructed a Neural Network architecture suitable for the derivation of T eff {T}_{{\rm{eff}}} , log g \log g , [ M / H ] \left[M\hspace{0.1em}\text{/}\hspace{0.1em}H] , and v e sin i {v}_{e}\sin i . The network was constrained by applying it to databases of AFGK synthetic spectra at different resolutions. Then, parameters of A stars from Polarbase, SOPHIE, and ELODIE databases are derived, as well as those of FGK stars from the spectroscopic survey of stars in the solar neighbourhood. The network model’s average accuracy on the stellar parameters is found to be as low as 80 K for T eff {T}_{{\rm{eff}}} , 0.06 dex for log g \log g , 0.08 dex for [ M / H ] \left[M\hspace{0.1em}\text{/}\hspace{0.1em}H] , and 3 km/s for v e sin i {v}_{e}\sin i for AFGK stars.

China officially launched the lunar exploration project, named “Chang’e Project,” in 2004. Then, in 2013, Chang’e-3 completed the soft landing on the lunar surface, starting a series of studies on the soft landing of spacecraft. This study aims to optimize the dynamic flight guidance and attitude control of the lunar landing module represented by Chang’e-3 in the soft landing stage. After analyzing the attitude control requirements of the soft landing stage of the lunar landing module, this study designs the lunar soft landing process under a variable structure sliding mode (VSSM) control. The study also analyzes the influence of the pulse width modulator (PWM) on the soft landing process. The simulation model of the lunar soft landing guidance and control system is established by MATLAB/Simulink, and the traditional proportional–integral–derivative (PID) control mode is compared with the interference condition. Results show that VSSM + PWM is superior to PID in robustness and accuracy and has a theoretical reference value for future lunar landing exploration and even Mars landing exploration.

In view of the future development trend of ocean altimetry satellites, the design idea of Ka/C dual frequency combination system is proposed, that is, the mode of using an altimeter antenna to contain Ka and C frequencies (35.7 and 5.3 GHz, respectively) for combined ranging. First, the random error model of altimeter measuring the distance from the altimeter phase center to the sea surface is given, and the analysis shows that the ionospheric correction error is one of the important factors. Second, the calculation of typical ionospheric parameters shows that the influence of ionospheric higher order terms on altimeter ranging is below the mm level, and its influence can be ignored. The rigorous expression for the first-order and second-order term correction of ionosphere error are given, respectively, by using dual frequency and three frequencies. The computational experiment of Jason-2 and SARAL satellite show that the maximum magnitude of ionospheric error correction in Ku band can reach 11 cm, while the maximum magnitude of ionospheric error correction in Ka band can reach 2 cm. For high-precision applications, ionospheric corrections must be made for single Ka frequency. After Ka/C dual frequency combination is adopted, error correction can be directly conducted without global ionospheric map (GIM) model, and its accuracy will be further improved than GIM model. Under 1 Hz sampling conditions, the ionospheric correction accuracy of Ka/C combination can be better than 2.5 mm, basically eliminating the influence of the ionosphere, and the total ranging accuracy can reach 3.5 cm considering the propagation error.

Asteroid capture holds great significance in understanding the origins of asteroids, the source of life, and the exploration of planetary mineral resources. To ensure the success of a mission aimed at capturing asteroids, it is crucial to choose asteroids that can be naturally captured by Earth. This article focuses on the orbital characteristics of temporarily captured asteroids. Through a statistical simulation of asteroid motion and an analytical derivation of the Jacobian integral, the necessary conditions for the temporary capture of asteroids by Earth are calculated. The analysis results show an approximately linear relationship between the orbit elements of temporarily captured asteroids. This condition is used to screen the currently observed near-Earth asteroids and has identified asteroids such as 2006 RH120 and 2020 CD3, which have been temporarily captured by Earth. These findings provide important suggestions for future asteroid capture missions and target selection.

A comprehensive photometric study and evolutionary state for the systems V0487 Lac, V0566 Hya, and V0666 Lac were carried out by means of their first photometric observations. New times of minima were estimated from the observed light curves, and first (O–C) curves were established for all systems. The radiative treatment was carried out using a Windows interface version of the Wilson and Devinney programme (W–D). The adopted models provide some absolute characteristics for the systems under study, which are used to determine the spectral type of the system’s constituents and their evolutionary stage. Distances to each system were calculated, and physical properties were estimated. All system components, with the exception of the secondary component of the system V0487 Lac, showed good fit when the systems were positioned on the theoretical mass–luminosity and mass–radius relations.

The main belt asteroids 4747, 5255, 11411, 15433, and 17866 were studied at the Baldone Astrophysical Observatory in the time span range 2018–2022. The obtained light curve data together with published Minor Planet Center data are analyzed with Fourier series, Lomb-Scargle periodogram, and phase dispersion minimization methods. A plan of analysis is given. The results computed from different observatories’ data are compared, and mean-weighted periods are obtained.

This work introduces the instruments’ design of multi-directional medium-energy electron detector (energy range: 30–770 keV) and high-energy electron detector (energy range: 400 keV to 5.8 MeV) deployed on one of the BeiDou navigation satellites in medium earth orbit. Through the electromagnetic compatibility design, the problem of the detector signal being susceptible to electromagnetic interference is solved and the lower detection limit reaches a very low level of 20 keV. The proton contamination in the electron measurement can be effectively removed by designing the light-blocking layer and the logical working mode of the sensors. The detector circuits and sensor structure are optimized and the miniaturization of the instrument is realized. This study also introduces the calibration method of the detectors, and gives the ground test results, which can provide a basis for the on-orbit calibration and data processing of the instrument.

BeiDou Medium Earth Orbit moderate-energy electron detection data play an important role in space environment effect analysis including satellite anomaly diagnosis, satellite risk estimation, etc. However, the data contain outliers which cause obstacle for the subsequent usage significantly. To solve this problem, we propose an outlier detection method based on convolutional neural networks (CNNs) which can learn a rule from labeled historical data and detect outliers from the detection data. With this method, we can identify outliers and do some follow-up operations to improve the data quality. In comparison with general methods, this CNN method provides a more reliable and rapid way to build dataset for the follow-up work.

A low-energy ion spectrometer (LEIS), onboard a Chinese navigation satellite in geosynchronous orbit, is one of the primary instruments for plasma detection. The LEIS is implemented by combining a top-hat electrostatic analyzer with a pair of angular scanning deflectors, which enables us to achieve in situ measurement of energetic ions in three-dimensional (3D) space with a large field of view of 360° × 90° and a wide energy range from 50 eV to 25 keV per charge. The key performance parameters including analyzer constant, geometric factor, linear relation function between elevation angles and deflector voltages, and the energy or angular resolutions have been determined by using detailed simulations and calibration experiments on the ground. The preliminary results from on-orbit observations demonstrate that the capability of the present LEIS payload can well meet the mission requirements for sampling the low-energy ion distributions in 3D space, measuring the negative satellite surface potential, and monitoring the magnetospheric storm or substorm activities.

Space radiation particles will cause a variety of radiation effects on orbiting satellites, such as single event effects, total ionizing dose, displacement damage, etc. In response to these space radiation effects, BeiDou Navigation satellites M15/M16 operating in medium earth orbit (MEO) developed the first integrated monitor for high-energy proton and particle radiation effects, based on space particle radiation detection technology. This payload realizes the joint observation of the high-energy proton environment, particle radiation linear energy transfer spectrum, and total radiation dose in the MEO. According to the detection data, research on the characteristics and laws of the space particle radiation effects can be carried out, and the problem of spacecraft reliability verification in orbit can be solved from the causal chain. In this article, we have introduced the high-energy proton detector (energy range 3–300 MeV), including technical indicators, working principles, instrument design, and ground calibration.

The orbit of BeiDou satellite system is a very ideal space environment monitoring area. The radiation dosimeters are present on this series of navigation satellites, and they are respectively installed in the x, y and z positions. A charge detector installed in the satellite cabin is used for monitoring satellite deep charging potential. Radiation dosimeters select the 100 nm P-channel metal oxide semiconductor (PMOS) sensors, whose monitoring range can reach 2 × 10 6  rad (Si). In the circuit design part, the “zero temperature coefficient” current of the PMOS is used as the constant current source for measuring, which effectively reduces the influence of temperature effect. Three radiation dosimeters realize the daily dose change monitoring during the satellite’s operation, and the detection accuracy is high. The deep charging potential sensor adopts the equivalent capacitor design which is composed of the outer optical quartz glass and the inner circular gold-plate. The two kinds of detection instruments have the characteristics of small volume, low power consumption and high detection accuracy. The detection results show that they have important application value for space environment prediction and guarantee.

Most of the satellites of the BeiDou navigation system work in geostationary orbit (GEO) and medium earth orbit (MEO), where the space plasma environment can make a severe impact on spacecraft. To measure the parameters of the plasma environment in GEO and MEO orbital space and to improve the design of the environmental adaptability of the satellites based on in situ probe data, a 2π-solid-angle omnidirectional field-of-view plasma detector was investigated and tested. The overall system design and detailed design of the structure and electric system were implemented. Then tests and verification were carried out to validate the reliability and capability of the detector. The detector can supply accurate in situ data of the plasma environment and be used to investigate the space plasma environment and its effects.

Based on the typical dielectric materials and devices of satellite, a surface charging and dose monitor (SCAD) was developed to measure the surface charging voltage, current, and dose under different shielding depths. The SCAD has been successfully launched into orbit on June 23, 2020. The measurement results on orbit show that the SCAD works normally, and the data of SCAD are reasonable. The results show that the radiation dose rate on geosynchronous orbit is about 0.4 mrad(Si)/s, and the maximum charging voltage is about −800 V during the initial measuring period. The charging voltage is consistent with the trends of geomagnetic disturbance Kp index. The on-orbit data provide basic data on surface charging and discharging effect and total dose effect, supporting the safe and reliable operation of the satellite.

The single event effect caused by space heavy ion radiation is one of the important factors affecting the safety and operation of spacecraft on orbit. In the research and evaluation of the frequency, spatial distribution and time characteristics of single event effects, linear energy transfer (LET) spectra of space radiation play an important role. On the Beidou navigation M15 and M16 satellites, a single event upset (SEU) and LET monitor was developed to obtain the upsets of the memory device and the LET spectra of space radiation which passes through the device. Through the measurement results from this monitor, the correlation between the device’s SEUs and the LET spectra could be studied.

Combining the anomalies and environmental monitoring data of the early stage Beidou satellites, the space radiation environment spatial/temporal distribution and space radiation effect risk characteristics are analyzed, and the dynamic characteristics of space environmental factors, such as hot plasma, high-energy electron and solar proton are summarized. The systematic joint monitoring for surface charging, internal charging, single event effect and total dose effect with corresponding space environment factors is proposed. The detector types, measurement parameters range and engineering constraints are allocated, and the engineering application and scientific research of detection data are prospected.

Low-energy ion detection in space is one of the most important interests of space exploration. An accurate calibration of this type of instrument is necessary to ensure the effectiveness and scientificness of the obtained data. And the ion source is the most critical equipment in a calibration facility. In this study, an ion beam system based on Kaufman ion source is designed, which can meet the ground calibration of space low-energy ion detection instrument in the low-energy range of 100–1,000 eV. The experimental research shows that when the beam intensity of the ion source is about 100 mA, the Faraday Cup collects about 1 mA of current, and the generated ion beam fluctuates less than 5% within 60 min, which can meet the ground calibration requirements of space low-energy ion detection instruments.

L, T, and Y brown dwarf (BD) exploration is a topical issue. First, the transition boundary between planets and BDs is not fully understood yet. Second, there is a phenomenon called the L/T-transition. The observed properties of cooler BDs differ significantly from the less cool ones, namely, colors of BDs shift much bluer and, simultaneously, dwarfs become brighter with a decrease in temperature. Models of this phenomenon are now being actively developed, for which reason BDs observed in a wide range of spectra are needed. Our goal is to refine the position of BDs in the parameter space of colors and magnitudes in order to effectively search for them in photometric surveys (without involving spectroscopic observations). For that reason, we crossmatched about 500 known L, T, and Y BDs with large photometric surveys. We paid special attention to the problem of identifying objects near the Sun because the crossmatching by default is made by searching for the closest object in a particular survey, which can be inappropriate concerning the high proper motions of our dwarfs. We have determined the color indices that can be used to search for these objects in large photometric surveys, and we have pointed out the color indices that are inappropriate for this purpose. We also made preliminary estimates of the radius matching to search for objects in the modern photometric surveys, given their proximity to the Sun and, consequently, their high proper motion.

Magnetic fields of various astrophysical objects are described using the dynamo mechanism. Corresponding equations in the three-dimensional case are quite difficult to be solved. So, the two-dimensional models can be useful for such problems. For galactic and accretion discs, it is convenient to use the no- z z approximation. The initial conditions for the magnetic field have a special interest. It seems that the seed field is generated by the Biermann mechanism, and after that they are transformed by the small-scale dynamo which gives a random structure of the field. Previously it has been shown that random initial conditions can lead to generation of large-scale magnetic field structures which correspond to the galaxies at the moment. In this work, we have studied generation of the magnetic field for the case of Kepler rotation curve, which is mostly suitable to the accretion discs. Here, we have studied the field generation in the thin disc for rapidly changing angular velocity in the case of simple model assumptions.

The majority of quasars detected at high redshifts ( z ≳ 6 z\gtrsim 6 ) strongly emit ultraviolet radiation with absolute magnitudes at rest-frame M 1450 Å , A B ∼ − ( 29 – 27 ) {M}_{1450\mathring{\rm A} ,AB}\hspace{0.33em} \sim \hspace{0.33em}-\left(29\hspace{0.1em}\text{–}\hspace{0.1em}27) . Some of them have high luminosities in [CII] 158 μ m 158\hspace{0.33em}{\rm{\mu }}{\rm{m}} line and in far-infrared (FIR) continuum, which leads to the expectation of a large amount of much cold dusty gas in these quasars. We have studied the relation between luminosities in the [CII] 158 μ m 158\hspace{0.33em}{\rm{\mu }}{\rm{m}} and the FIR continuum for a slightly absorbed supermassive black hole (SMBH) obscured by an ensemble of dense clouds with a low covering factor. We have found that dense clouds with a low covering factor can give sufficient luminosities in [CII] 158 μ m 158\hspace{0.33em}{\rm{\mu }}{\rm{m}} line and the underlying FIR continuum to reproduce the [CII]-FIR ratio observed in high-redshift quasars for a reasonable SMBH mass of M • ∼ 1 0 9 M ⊙ {M}_{\bullet }\hspace{0.33em} \sim \hspace{0.33em}1{0}^{9}{M}_{\odot } . We note that many distant mildly/heavily obscured active galactic nuclei are to avoid detection in near-infrared (IR) wavelengths; if this is the case, blind IR/FIR surveys are needed.

In accordance with the principles of open science, the results of the research should remain available for further investigations and practical interaction with them in the research community. Such results include collected initial and obtained data, specifications and implementations of methods applicable to them including data integration rules, and other possible resources. At the same time, the results of research on data should be curated to maintain their relevance, compliance with domain development, and standards in order to make them as useful as possible in the long term. A research support system in the research domain of physics of stellar systems is being developed to provide relevant data and methods, classify them, make them findable, avoid multiple integration of heterogeneous data, and integrate them into ongoing research in the astrophysical community. New catalogues are being added on regular basis, and this process is accompanied by correct cross-identification of the entities. New observational types of binary stars with their features are added to binary star database (https://bdb.inasan.ru).

We present a study of the interstellar medium parameters in star-forming complexes (SFCs) in NGC 3351, NGC 5055, and NGC 5457 galaxies. This study concludes our previous investigations of gas and dust in a number of spiral galaxies. The data for the three galaxies confirm the following. There is a tight correlation between near-infrared and far-infrared luminosities of the extragalactic SFCs. Emission at 8 μm also shows a strong correlation with the carbon monoxide emission. Atomic and molecular gas masses do not show any strong correlation with the corresponding velocity scatters; however, in NGC 5055, we see a hint of the SFC with the largest velocity scatter being located at the galaxy periphery.

In this article, we consider the problem of the evolution of the disk subsystem of galaxies, taking into account their halos. The global structure of the disk of galaxies strongly depends on the mass and shape of the halo. To this end, we have studied the evolution of nonradial oscillations of a nonstationary disk surrounded by a passive ellipsoidal halo with a uniform density. A system of equations for the evolution of a self-gravitating disk is obtained, taking into account the halo, in the form of matrix differential equations, and a method for its numerical analysis is developed to study the effect of the halo on disk formation. Numerical calculations were performed for various values of the system parameters, such as the initial perturbation, the circular speed of disk rotation, the ratio of the mass of the halo to the mass of the disk, and the time dependences of the major and minor semiaxes of the disk. The critical values of the system parameters are determined at which the halo stabilizes nonlinear and nonradial oscillations of the disk subsystem of galaxies at an early stage of their evolution.

The present study is a review of publications regarding special aspects of the mineralogy of the Kaba meteorite, clay minerals, hydrous phases, and organic matter. In Section 1, the history of fall and finding of the meteorite and the first classical mineralogical description in the Year 1961 are mentioned. The most frequent alteration product of primary silicates and the glassy matrix is Fe-bearing saponite. By modelling of hydrothermal alteration of Allende-type meteorites, artificial saponite could be produced. The thermodynamic study proved the possibility of hydrous neoformation of silicates and magnetite at low temperatures, mostly below 100°C. The formation of Fe-rich external rims in forsterite grains by hydrothermal action was demonstrated by electron probe microanalysis and scanning electron microscopy-cathodo-luminescence methods. Foliation in CV3 carbonaceous chondrites indicates that the Kaba meteorite is derived from the external, shallow zone of the parent body. A combination of X-ray power diffraction (XRD) and Mössbauer spectroscopy made the exact modal analysis of CV3 chondrites possible, including Kaba. The study of alteration by in situ determination of stable oxygen isotope contents may provide constraints regarding the oxygen isotopic composition of the aqueous fluid on the CV parent asteroid. The degree of thermal metamorphism of the organic matter was determined by using Raman spectroscopy. The presence of aromatic and aliphatic, saturated and unsaturated hydrocarbons, and various amino acids was demonstrated. The non-biogenic origin is more probable; however, there are textural and mineralogical observations that may indicate also the biogenic origin of organic matter. In addition to the review of the literature above, as an appendix, shortly new XRD investigations of the authors are reported that indicated smectite-like phases in a thin section made of the meteorite.

We extend Einstein’s theory of general relativity by introducing stochastic elements in addition to the usual fields and apply it to explore late-time redshift. The stochastic perturbation of spacetime enforces an effective minimum length (ML) to give us a cosmological constant naturally derived from the diffusive nature of spacetime and a redshift driven by both the geometry of spacetime as well as its diffusive nature. In this new theory, “dark energy” is the manifestation of fundamental uncertainty caused by ML of spacetime. The new theory converges to the minimal Λ \Lambda CDM model in the era after the Big Bang, when the geometry dominates over the diffusive character of spacetime. However, as the Hubble parameter decreases in value over time, there is a period during which the diffusive effects play an increasingly important role. For later times, as the universe approaches its minimum total energy density, the resulting redshift obtains significant contributions from both the geometry, captured by the Hubble parameter “ H H ,” and spacetime diffusion, captured by a new parameter “ D D ,” the diffusive equivalent to H H . Hence, the new theory presented here is particularly important during the later times in which H H diminishes and becomes comparable to D D . The theory suggests that the Hubble tension might be relieved by the diffusive character of spacetime. In order to compare the early time Hubble parameter estimates to the late-time estimates, we must recognize the contribution diffusion makes to the redshift observations and further reformulate luminosity distance and its kinematic expression to account for the effects of diffusion in addition to geometry. We perform a simple analysis of Type Ia supernovae observations with distances calibrated using Cepheids to obtain estimates for the new diffusion parameter. Based on these results, the new theory places the universe well inside a vacuum-dominated regime with a small and diminishing diffusion parameter.

In 2007, Storti predicted that the value of the cosmic microwave background radiation (CMBR) temperature may be improved: from the particle data group (PDG) value of [ T 0 = 2.725 ± 0.001 K] to [ T 0 = 2.7254 K]. In 2011, the PDG revised their value of CMBR to [ T 0 = 2.7255 ± 0.006 K]. In 2008, Storti predicted a Λ CDM Hubble constant of [ H 0 = 67.0843 km/s/Mpc]. In the same year, the PDG published their value as being [ H 0 = 73 ± 3 km/s/Mpc]. In 2013, the PDG published a revised value of [ H 0 ] as being considerably lower [ H 0 = 67.3 ± 1.2 km/s/Mpc]. These predictions and experimental confirmations, in particular the value of [ H 0 ] being successfully predicted 5 years in advance of the Planck collaboration and without Planck satellite instrumentation, demonstrate the power of the technique applied. We utilize the same technique to calculate the present values of Λ CDM [ H 0 ], [Ω Λ ], [Ω M ], [ q ], and [Λ]. Subsequently, we describe the complete history of the cosmos from the instant of the Big Bang to the present epoch, in complete agreement with the standard model of cosmology. Moreover, we explicitly demonstrate that the Hubble tension does not exist, in a companion publication to this research article. This is achieved by utilizing a single equation to calculate both values of Hubble constant associated with the Hubble tension.