Astronomy Reports最新文献

{"title":"Analyzing Doublet Type II Radio Bursts During Solar Cycles 23 and 24: Key Characteristics and Trends","authors":"Charita Pant,&nbsp;Bimal Pande,&nbsp;Raj Kumar,&nbsp;Seema Pande","doi":"10.1134/S1063772924600316","DOIUrl":"10.1134/S1063772924600316","url":null,"abstract":"<p>This paper presents a statistical analysis of doublet type II radio bursts, specifically the first type II (type II₁) and the second type II (type II₂), during solar cycles 23 and 24. The study focuses on radio-rich CMEs that are accompanied by type II solar radio bursts, covering a period of 15 years from November 1997 to December 2015. The characteristics of these doublet type II radio bursts were analyzed using data from the Culgoora radio spectrograph. Key parameters such as lifetime, start frequency, end frequency, bandwidth, drift rate, and estimated shock speed (ESS) of both the types of radio burst were examined. During solar cycles 23 and 24, the start frequencies of first type II bursts were generally higher than those of the second type II bursts, suggesting different driving mechanisms for the two types. A good correlation was found between start frequency and drift rate throughout the study period, with correlation coefficients of <span>(r = 0.5)</span> for solar cycle 23 and <span>(r cong 0.9)</span> for solar cycle 24. This indicates that doublet type II radio bursts consistently drift from a high start frequency to a low end frequency, reflecting the rapid propagation of the shock away from the sun. However, the correlation between other solar parameters, such as lifetime, bandwidth, drift rate, and ESS was weak, implying that various drivers or mechanisms might influence the occurrence of these radio bursts. Additionally, the ESS of the first type II bursts was observed to be greater than that of the second type II bursts suggesting that doublet type II radio bursts may originate from eruptions of different structures.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1335 - 1348"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fourier Series Methodology for Exploring the Periodic Orbits in the CR3BP with Spherical Primaries","authors":"Om Prakash Meena,&nbsp;Himanshu Aggarwal,&nbsp;Harsh Mishra,&nbsp;Khush Shaw,&nbsp;Rajiv Aggarwal","doi":"10.1134/S1063772924600365","DOIUrl":"10.1134/S1063772924600365","url":null,"abstract":"<p>In this paper, we have scrutinized the circular restricted three-body problem (CR3BP) while considering both primaries as spherical. We have determined the positions of the libration points and their stability using the dynamics of the third body. Furthermore, we have drawn the periodic orbits by retaining the terms up to third order in the Fourier series expansion. Consecutively, the variation in time period of the periodic orbits impacts the networks of long- and short-period orbits in terms of its shape, size and time period. After that, two models of our solar system are examined using the procedures outlined in this manuscript.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1317 - 1334"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acetylene Trimerization on the Silicon Carbide Surface in the Envelopes of AGB Stars: An Astrochemical Estimation","authors":"M. S. Murga","doi":"10.1134/S1063772924700999","DOIUrl":"10.1134/S1063772924700999","url":null,"abstract":"<p>This work is devoted to estimating the contribution of the trimerization reaction of acetylene molecules on the surface of silicon carbide (SiC) particles with the formation of benzene molecules into the benzene abundance in the envelopes of asymptotic giant branch (AGB) stars. The reaction was included into an astrochemical model, which is used to simulate conditions corresponding to the envelope of the AGB star IRC+10216. The calculation results show that the acetylene trimerization reaction on the SiC surface can effectively occur under the conditions of the envelopes of AGB stars and have a significant effect on the benzene abundance, and, as a consequence, other aromatic molecules. Accounting for acetylene trimerization can increase the benzene abundance in the gas by an order of magnitude. The benzene abundance on the dust surface can be up to four orders of magnitude higher than the estimates for the gas phase predicted by the model with gas-phase reactions only. The rate of benzene formation on the SiC surface significantly exceeds the rate of benzene formation in the gas during the early phases of the star’s pulsation. The efficiency of benzene formation in the trimerization reaction and its transition to gas depends on the currently unknown kinetic parameters of the reaction, in particular, on the desorption energy of the resulting benzene molecule. Determining the reaction parameters will help to perform more accurate quantitative modeling in the future.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1176 - 1184"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"To the Question of North–South Asymmetry of Solar Activity in the 25th Schwabe–Wolf Cycle","authors":"S. A. Yazev,&nbsp;E. S. Isaeva,&nbsp;V. M. Tomozov,&nbsp;K. I. Ivanov,&nbsp;B. Hos-Erdene","doi":"10.1134/S1063772924701051","DOIUrl":"10.1134/S1063772924701051","url":null,"abstract":"<p>An analysis of the north–south asymmetry (NSA) of the groups of sunspots and flares location during the growth phase of the 25th Schwabe–Wolf cycle of solar activity was performed. During the first four years of the cycle’s development, sunspot activity increased quasi-synchronously in the northern and southern hemispheres; the absolute value of the NSA coefficient during this period decreased from 0.6 to 0.2. The longitudinal distribution of sunspots in the second half of 2023 was uneven and similar in both hemispheres; groups of sunspots appeared during this period mainly in the longitudinal intervals of 30°–100°, as well as 200°–280°, while at other longitudes activity was reduced both in the northern and in the southern hemispheres. The number of flares of all classes was 45% in the northern hemisphere, 42% in the southern hemisphere, and 13% were not identified. The flare index was distributed between the hemispheres in the ratio of 49.5 to 42, with 8.5% not identified. A comparison with the 24th cycle shows that NSA in the distribution of sunspots and flares between the northern and southern hemispheres in the current (25th) cycle is significantly lower than in the previous one. A high degree of symmetry of activity can ensure a greater height of the 25th cycle compared to the 24th, as well as the single-peaked nature of the 25th cycle. It is hypothesized that the 25th cycle exhibits a higher level of dipole parity of the global magnetic field compared to the 24th cycle.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1209 - 1216"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Activity of Star TOI-1408 and Mass Loss by the Atmospheres of Its Exoplanets","authors":"I. S. Savanov","doi":"10.1134/S1063772925701288","DOIUrl":"10.1134/S1063772925701288","url":null,"abstract":"<p>The properties of the TOI-1408 multiplanetary system consisting of hot Jupiter (planet (b), <span>((1.86 pm 0.02){kern 1pt} {{M}_{{{text{Jup}}}}})</span>, <span>((2.4 pm 0.5){kern 1pt} {{R}_{{{text{Jup}}}}})</span>) and sub-Neptune (planet (c), <span>((2.22 pm 0.06){kern 1pt} {{R}_{ oplus }})</span>, <span>((7.6 pm 0.2){kern 1pt} {{M}_{ oplus }})</span>) orbiting a star of spectral class F have been considered. Measurements of radial velocities have also indicated the existence of an additional celestial body with an orbital period of several thousand days. The TOI-1408 system has made it possible to study the migration processes of hot Jupiter-type planets in cases, where less massive planet (c) is closer to the star than more massive one (b). Based on archival measurements of the TOI-1408 brightness (DASCH project), we have estimated the length of the possible cyclic long-term variability of the object (~10 500 days). The analysis of the brightness variability of TOI-1408 according to the Kamogata Wide-field Survey (KWS) archive has led to the detection of peaks in the power spectrum corresponding to a rotation period of ~7.5 days. The mass loss of the planets atmospheres, which have been established for two values of parameter <span>(log R_{{{text{HK}}}}^{'})</span> (<span>( - 4.94)</span> and <span>( - 4.59)</span>) corresponding to the maxima of the bimodal distribution of this parameter for low and high activity for stars of spectral class F, has been estimated. The mass loss of planet (b) (hot Jupiter) can reach <span>(2.3 times {{10}^{{11}}})</span> g/s and of the sub-Neptune—planet (c) can reach <span>(2.7 times {{10}^{{10}}})</span> g/s for the value of <span>(log R_{{{text{HK}}}}^{'} = - 4.59)</span>. The obtained data have been in good agreement with the results for exoplanets of the corresponding types (including for hot Jupiter HD 189733 b and warm Neptune GJ 436 b).</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1266 - 1270"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Searching for Biomarkers with Spektr-UF Observatory: Nitric Oxide Molecule in Atmospheres of Exoplanets near the Active Host Stars","authors":"G. N. Tsurikov,&nbsp;D. V. Bisikalo,&nbsp;V. I. Shematovich,&nbsp;A. G. Zhilkin","doi":"10.1134/S1063772925701355","DOIUrl":"10.1134/S1063772925701355","url":null,"abstract":"<p>Detection of an N₂–O₂ atmosphere on an Earth-like exoplanet may be one of the defining pieces of evidence for the presence of biological and geological activity on it. The nitric oxide molecule, in turn, is an indicator of such an atmosphere, and its spectral bands in the near UV range (γ-bands, 203–248 nm) can be potentially detected using a long-slit spectrograph (LSS) (resolution <i>R</i> = 1000) of the planned launch of the Spektr-UF space telescope (ST). Strong electron precipitations into the atmospheres of exoplanets that are in the potentially habitable zone near the active host stars can lead to an increase in the concentration of NO and, accordingly, increase the chances of detecting this biomarker. Based on the calculations using models of electron precipitation into the upper atmosphere of the planet, odd nitrogen chemistry, radiative transfer, and the Spektr-UF exposure time calculator, we determined the necessary observational conditions for detecting the NO biomarker. Thus, in a reasonable observational time (≤ 200 hours) with a signal-to-noise ratio of 3, using the Spektr-UF, it is possible to detect γ-bands of NO in the atmospheres of typical super-Earths and sub-Neptunes that are subjects of strong electron precipitation—at distances of up to 8 and 30 parsecs, respectively. The best observational targets for NO detection are exoplanets in the potential habitable zone near host stars with G–K spectral types.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1406 - 1422"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Displacement Norm in the Presence of an Inverse-Square Perturbing Acceleration in the Reference Frame Associated with the Velocity Vector","authors":"T. N. Sannikova","doi":"10.1134/S106377292570129X","DOIUrl":"10.1134/S106377292570129X","url":null,"abstract":"<p>The problem of motion of a zero-mass-point under the action of attraction to the central body and a small perturbing acceleration <span>({mathbf{P}}{kern 1pt} ' = {mathbf{P}}{text{/}}{{r}^{2}})</span> is considered, where <span>(r)</span> is the distance to the attracting center and components of the vector <span>({mathbf{P}})</span> are assumed to be constant in a reference system with the axes directed along the velocity vector, the main normal, and the angular momentum vector. Previously, for this problem, equations of motion in the mean elements and formulas for the transition from osculating elements to the mean ones in the first order of smallness were found; second-order quantities are neglected. If the perturbing forces are small, then the osculating orbit slightly deviates from the mean one. The difference <span>(d{mathbf{r}})</span> between the position vectors on the osculating and mean orbit is a quasi-periodic function of time. In this work, the Euclidean (root-mean-square over the mean anomaly) norm <span>({{left| {d{mathbf{r}}} right|}^{2}})</span> of the displacement of the osculating orbit relative to the mean one is obtained. It turned out that <span>({{left| {d{mathbf{r}}} right|}^{2}})</span> depends only on the components of the vector <span>({mathbf{P}})</span> (positive definite quadratic form), the semi-major axis (proportional to the second power), and the eccentricity of the osculating ellipse. The norm <span>({{left| {d{mathbf{r}}} right|}^{2}})</span> is obtained in the form of a series in powers of eccentricity <span>(e)</span>. The resulting expression holds up to <span>({{e}_{0}} approx 0.995862)</span>; for <span>(e &gt; {{e}_{0}})</span>, <span>(varrho = sqrt {{{{left| {d{mathbf{r}}} right|}}^{2}}} )</span> can take complex values. The results are applied to the problem of the motion of model bodies under the action of perturbing acceleration caused by the Yarkovsky effect. A comparison of the results with similar ones for the norm <span>({{left| {d{mathbf{r}}} right|}^{2}})</span> in the reference system associated with the radius vector was also carried out.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1291 - 1302"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D Numerical Model for Studying Electron Precipitation in the Upper Atmospheres of Venus-Like Exoplanets","authors":"A. G. Zhilkin,&nbsp;V. I. Shematovich,&nbsp;G. N. Tsurikov,&nbsp;D. V. Bisikalo","doi":"10.1134/S1063772925701252","DOIUrl":"10.1134/S1063772925701252","url":null,"abstract":"<p>In the paper, a three-dimensional numerical model of solar wind plasma flow around a terrestrial planet that does not have its own magnetic field has been present. The model has been based on the approximation of multicomponent magnetohydrodynamics and has taken into account ionization and recombination processes. The numerical model has been validated using the example of the magnetosphere of Venus. Our model, in particular, has made it possible to calculate the structure and parameters of electron precipitation into the planet’s ionosphere. The developed model has been supposed to be used to study observational manifestations of the NO potential biomarker in the atmospheres of exoplanets without their own magnetic field.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1252 - 1265"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Stability of a Layered Inhomogeneous Elliptical Galaxy as a Dynamic System","authors":"S. A. Gasanov","doi":"10.1134/S1063772925701240","DOIUrl":"10.1134/S1063772925701240","url":null,"abstract":"<p>In this paper, several new models of a layered inhomogeneous elliptical galaxy (EG) having the shape either a triaxial ellipsoid or an oblate or prolate spheroid and consisting of baryonic mass and dark matter with different laws of density distribution or profiles have been considered. Based on these models, some key dynamic parameters of the EG have been determined: gravitational (potential) energy and rotational kinetic energy, angular momentum distribution and specific angular momentum depending on density profiles. The equilibrium and stability (instability) of the EG as a dynamic system have been established according to known criteria. Critical values of parameters of the family of spheroids that determine the boundaries of stability (or instability) dynamic system based on the values of specific angular momentum depending on the density profiles have been found. The obtained results have been applied to sixty model EGs with parameters exactly matching those that actually exist and are presented in the form of tables and figures.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1217 - 1238"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spot and Flare Activity of Single G5 III–IV Giant HD 199178 from TESS Observations","authors":"I. S. Savanov,&nbsp;A. N. Tarasenkov,&nbsp;E. S. Dmitrienko","doi":"10.1134/S1063772924701002","DOIUrl":"10.1134/S1063772924701002","url":null,"abstract":"<p>The aim of our paper has been to study the activity of the FK Com type star rapidly rotating G5 III–IV giant HD 199178 (V1794 Cyg) based on available photometric data from the TESS mission in five sectors. The light curves of the star characterized the variability caused by rotational modulation due to the presence of cool spots on the surface, power spectra, and phase diagrams have been studied. In the power spectrum, based on the combined data of all observation sectors, the dominant peak has corresponded to the photometric period of <span>(P{{ = 3.28}^{d}} pm {{0.12}^{d}})</span>. It has been suggested that a decrease in the <span>(P)</span> value over time (over an interval of ~40 years) from 3.337^<i>d</i> up to 3.28^<i>d</i> may be due to the long-term evolution of the positions of the active areas (spots) on the surface of a differentially rotating star. The changes in the amplitude of the brightness variability and the shape of the phase curves of HD 199178 have been analyzed and it has been found that the fraction of the star’s surface occupied by spots varied from 7 to 12% of its surface area. The flare activity of the star has been studied. The parameters of the amplitude, duration, and energy of the flares have been determined for two flares. One of the considered flares is the strongest during the observations in five sectors (5.1 × 10³⁵ erg) and in magnitude can characterize the upper limit of the flare energies in a given state of star activity. Maps of the surface temperature inhomogeneities of the star have been constructed.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1153 - 1158"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}