Astronomy Reports最新文献

{"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}

{"title":"Spectroscopic Binary Cepheid AU Peg in the Gaia DR3 Epoch: Effect of Ellipsoidality, Mass, and Evolutionary Status","authors":"A. S. Rastorguev,&nbsp;M. V. Zabolotskikh,&nbsp;N. A. Gorynya","doi":"10.1134/S1063772925701409","DOIUrl":"10.1134/S1063772925701409","url":null,"abstract":"<p>The physical characteristics and evolutionary status of the spectroscopic binary Cepheid AU Peg, usually classified as a BL Her variable, is revised. Taking into account previously unpublished radial velocity measurements made with a radial velocity meter (RVM), the parameters of the relative orbit of the Cepheid and its companion are refined. Based on the available radial velocity measurements and photometric observations, a number of estimates of the Cepheid’s pulsating radius are made. Based on 74 new radial velocity measurements made in the period JD2453930–2459490 virtually simultaneously with the Gaia DR3 photometric observations (44 brightness measurements in the period JD256962–2457877), the mean radius of AU Peg is determined by the pulsating photosphere method equal to (16.0 ± 0.6) <span>({{R}_{ odot }})</span>; the amplitude of radius variations is about 0.7 <span>({{R}_{ odot }})</span>. For the first time, 2% brightness variations are found for a spectroscopic binary Cepheid in the G band with a half orbital period, the phases of which are clearly synchronized with the phases of the orbital motion (conjunctions and quadratures) and can be interpreted as a manifestation of the ellipsoidality effect of the main component filling the Roche sphere at 60–70%. The orbit of the binary system calculated on the basis of astrometric data from Gaia DR3 and radial velocities is limited by a torus with a thickness of |<i>z</i>| ≤ 300 pc and inner and outer radii equal to 7.2 and 8.8 kpc, respectively, while the vertical velocity lies within |<i>V</i>_<i>z</i>| ≤ 18 km/s. Based on the kinematics and abundance of heavy elements, AU Peg can certainly be classified as a representative of the typical population of a thin disk of moderate (∼1–3 Gyr) age, which completely excludes its classification as a BL Her variable. The Cepheid, which current mass, as follows from the magnitude of ellipsoidality, does not exceed ∼(0.85 ± 0.05) <span>({{M}_{ odot }})</span>, is at the evolutionary stage after the mass exchange in the subgiant phase with a companion - a main-sequence star, which is currently significantly more massive than the Cepheid.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1457 - 1469"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621830","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 TOI-3568 and Mass Loss of the Atmosphere of Its Exoplanet in the Sub-Jovian Desert","authors":"I. S. Savanov","doi":"10.1134/S1063772925701379","DOIUrl":"10.1134/S1063772925701379","url":null,"abstract":"<p>The properties of the TOI-3568 system, which has a super-Neptune-type planet and which by its properties falls into the region of the sub-Jovian desert, have been considered. TOI-3568 is a poorly studied dwarf of the spectral class K. Based on archival measurements of the brightness of TOI-3568 (Kamogata Wide-field Survey), the possible cyclic long-term variability of the object equal to 1.3, 1.7 and 4.1 years has been estimated. It has been found that TOI-3568 belongs to the number of old stars and can have only moderate or low activity. The mass loss from the planet’s atmosphere has been calculated using an approximation formula for the atmosphere loss model with an energy limitation. If the star is a low-activity K dwarf then <span>({{M}_{{{text{loss}}}}})</span> can be <span>(1.18 times {{10}^{9}})</span> g/s. If the star’s activity approaches the maximum for stars of this spectral class then the value of <span>({{M}_{{{text{loss}}}}})</span> will increase in 6.3 times. Our data are in an agreement with the results characterizing the general behavior of parameter <span>({{M}_{{{text{loss}}}}})</span> for other objects, including the hot Jupiter HD 189733 b and the warm Neptune GJ 436 b. The TOI-3568 system is of particular interest because it has made it possible to study rare objects located on the “mass-period” or “radius-period” diagrams of exoplanets in the region that covers the range between super-Earths and hot Jupiters (called the sub-Jovian desert) and which exhibits a deficit in the number of planets. The fact that TOI-3568 is an old star has provided a unique opportunity to trace the evolution of the properties of a planetary system currently located in the sub-Jovian desert.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1437 - 1441"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621770","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":"Possibility of Observing Photon Rings Using High-Frequency Space Radio Interferometry with Very Long Bases","authors":"A. G. Rudnitskiy,&nbsp;M. A. Shchurov,&nbsp;A. V. Khudchenko,&nbsp;T. A. Syachina","doi":"10.1134/S1063772925701380","DOIUrl":"10.1134/S1063772925701380","url":null,"abstract":"<p>In the paper, the possibility of observing photon rings in the close vicinity of supermassive black holes using space very long baseline radio interferometry at a frequency of 600 GHz has been examined. The 600-GHz range is promising for such observations by very long baseline radio interferometry because high frequency reduces the contribution of radio emission scattering by the interstellar medium and also makes it possible to increase the angular resolution of the interferometer. High angular resolution and low scattering, in turn, have suggested the possible detection of photon rings in the close vicinity of supermassive black holes. To estimate these possibilities, modeling of the visibility amplitude distribution from the baseline projection has been performed, taking into account various possible sensitivity parameters of the interferometer. Based on the results, the prospects for the 600-GHz range in terms of observing photon rings have been shown. In addition, the requirements for the on-board receiving complex of a space interferometer have been formulated, at which detection of photon rings is feasible.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1442 - 1448"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621767","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":"The Difference in Gravitational Potentials at Two Ground Points Measuring Experiment Using the Duplex Satellite Method","authors":"A. V. Naumov,&nbsp;F. R. Smirnov,&nbsp;V. F. Fateev","doi":"10.1134/S106377292570132X","DOIUrl":"10.1134/S106377292570132X","url":null,"abstract":"<p>An experiment on measuring the difference in gravitational potentials and orthometric heights of two ground points using a quantum clock and a duplex satellite communication method was conducted for the first time in the Russian Federation. The measurement points were located in the territory of the Federal State Unitary Enterprise “VNIIFTRI” at a distance of 850 m from each other with a height difference of about 21 m. The Russian geostationary satellite Express-80 was used as a repeater, duplex communication was established using stationary and relocatable sets of duplex equipment. The difference in orthometric heights was measured with an accuracy of about 2.8 m.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":"68 12","pages":"1376 - 1384"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621829","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}