Subjects -> ASTRONOMY (Total: 94 journals)
 Showing 1 - 46 of 46 Journals sorted alphabetically Advances in Astronomy       (Followers: 50) Annual Review of Astronomy and Astrophysics       (Followers: 51) Annual Review of Earth and Planetary Sciences       (Followers: 68) Artificial Satellites       (Followers: 22) Astrobiology       (Followers: 12) Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society       (Followers: 8) Astronomical Review       (Followers: 6) Astronomische Nachrichten       (Followers: 5) Astronomy & Geophysics       (Followers: 50) Astronomy and Astrophysics       (Followers: 69) Astronomy and Computing       (Followers: 8) Astronomy Letters       (Followers: 23) Astronomy Reports       (Followers: 23) Astronomy Studies Development       (Followers: 16) Astroparticle Physics       (Followers: 11) Astrophysical Bulletin       (Followers: 5) Astrophysics       (Followers: 36) Astrophysics and Space Science       (Followers: 51) Astrophysics and Space Sciences Transactions (ASTRA)       (Followers: 61) Astropolitics: The International Journal of Space Politics & Policy       (Followers: 14) Celestial Mechanics and Dynamical Astronomy       (Followers: 16) Chinese Astronomy and Astrophysics       (Followers: 26) Colloid Journal       (Followers: 3) Comptes Rendus : Physique       (Followers: 3) Computational Astrophysics and Cosmology       (Followers: 7) Earth and Planetary Science Letters       (Followers: 149) Earth, Moon, and Planets       (Followers: 48) Earth, Planets and Space       (Followers: 78) EAS Publications Series       (Followers: 9) EPL Europhysics Letters       (Followers: 9) Experimental Astronomy       (Followers: 39) Expert Opinion on Astronomy and Astrophysics       (Followers: 9) Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society       (Followers: 5) Few-Body Systems       (Followers: 2) Foundations of Physics       (Followers: 41) Frontiers in Astronomy and Space Sciences       (Followers: 16) Galaxies       (Followers: 7) Globe, The       (Followers: 4) Gravitation and Cosmology       (Followers: 7) Icarus       (Followers: 72) International Journal of Advanced Astronomy       (Followers: 22) International Journal of Astrobiology       (Followers: 5) International Journal of Astronomy       (Followers: 23) International Journal of Astronomy and Astrophysics       (Followers: 37) International Journal of Satellite Communications Policy and Management       (Followers: 16) International Letters of Chemistry, Physics and Astronomy       (Followers: 9) ISRN Astronomy and Astrophysics       (Followers: 15) Journal for the History of Astronomy       (Followers: 21) Journal of Astrobiology & Outreach       (Followers: 6) Journal of Astronomical Instrumentation       (Followers: 4) Journal of Astrophysics       (Followers: 34) Journal of Astrophysics and Astronomy       (Followers: 59) Journal of Atmospheric and Solar-Terrestrial Physics       (Followers: 142) Journal of Geophysical Research : Planets       (Followers: 126) Journal of Geophysical Research : Space Physics       (Followers: 144) Journal of High Energy Astrophysics       (Followers: 26) Kinematics and Physics of Celestial Bodies       (Followers: 12) KronoScope       (Followers: 2) Macalester Journal of Physics and Astronomy       (Followers: 6) Monthly Notices of the Royal Astronomical Society       (Followers: 14) Monthly Notices of the Royal Astronomical Society : Letters       (Followers: 3) Nature Astronomy       (Followers: 17) New Astronomy       (Followers: 27) New Astronomy Reviews       (Followers: 20) Nonlinear Dynamics       (Followers: 20) NRIAG Journal of Astronomy and Geophysics       (Followers: 5) Physics of the Dark Universe       (Followers: 5) Planetary and Space Science       (Followers: 113) Planetary Science       (Followers: 53) Proceedings of the International Astronomical Union       (Followers: 3) Publications of the Astronomical Society of Australia       (Followers: 4) Publications of the Astronomical Society of Japan       (Followers: 5) Research & Reviews : Journal of Space Science & Technology       (Followers: 21) Research in Astronomy and Astrophysics       (Followers: 39) Revista Mexicana de Astronomía y Astrofísica       (Followers: 4) Science China : Physics, Mechanics & Astronomy       (Followers: 5) Science China Physics, Mechanics & Astronomy       (Followers: 5) Solar Physics       (Followers: 30) Solar System Research       (Followers: 16) Space Science International       (Followers: 126) Space Science Reviews       (Followers: 93) Space Weather       (Followers: 28) Transport and Aerospace Engineering       (Followers: 14) Universe       (Followers: 7)
Similar Journals
 Solar System ResearchJournal Prestige (SJR): 0.332 Number of Followers: 16      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1608-3423 - ISSN (Online) 0038-0946 Published by Springer-Verlag  [2469 journals]
• The 11-Year Magnetic Solar Cycle: Chaos Control Due to Jupiter

Abstract: The observed magnetic field of the Sun is believed to originate from a “dynamo-effect” in its convective surface layer. However, there is no natural 11-year timescale in such models. We show that this timescale in the mean naturally and automatically arise through magnetic “chaos-control” of the inherently chaotic solar dynamo, mainly due to Jupiter, while also conforming to real and observed sunspot characteristics.
PubDate: 2022-06-01

• The Mass Loss of the Main Asteroid Belt and Mars’ Zone Caused by the
Impact of Solar Radiation and Jupiter: I: Numerical Calculations of the
Dust Evolution

Abstract: — The values of the mass of Mars and the asteroid belt are one and three orders of magnitude, respectively, less than those theoretically predicted from the extrapolation of the density of a solid component of the protoplanetary disk in the vicinity of Venus and the Earth. This study focuses on the mass erosion of zones of the asteroid belt and Mars, which is caused by sweeping dust particles out of this region under the influence of solar radiation and Jupiter’s gravitation. The dynamics of small particles produced by collisions of bodies in a region of 1 to 3.4 AU is considered. The analysis of the calculated orbits has shown that more than 10% of small dust particles (0.2–40 μm), which are produced, for example, in each of the collisions of asteroids, gain substantial orbital eccentricities under the impact of solar radiation; they are scattered by the gravitational field of Jupiter and leave the Solar System for ~(3 × 104) years on average. This effect may explain a considerable mass loss of the asteroid belt and Martian zone. The effectiveness of sweeping dust particles from asteroids with weak gravity is confirmed by spaceborne images. As is seen in these images, the surface of small asteroids is speckled with stones, while the surface of the massive Moon is covered with fine dust, which is kept from escaping by the lunar gravitation.
PubDate: 2022-06-01

• The Role of Radial Transport in Forming Minor Bodies of the Outer Solar
System

Abstract: In this paper, we summarize the experimental data on the features of the mineral, chemical, and isotopic compositions of minor bodies of the Solar System—asteroids, Saturn’s satellites, and nuclei of comets of different dynamic types—which suggest that the formation of these bodies was significantly influenced by the mixing of different-genesis matter: presolar and nebular. The latter was formed in the circumsolar gas–dust protoplanetary accretion disk that is also called the nebula. The matter of presolar origin includes amorphous iron–magnesium silicates, refractory organic compounds, volatile organic compounds, amorphous water ice, as well as ices of СО2, NH3, CH3OH, CO, etc. The species of nebular origin are aluminum-, calcium-, and titanium-rich refractory inclusions (known as CAls), microcrystalline magnesium silicates, as well as crystalline water ice, the hydrogen isotopic composition of which is several times lower than that of water ice of the protosolar nebula. The presolar- and nebular-origin matter could be mixed because, in the circumsolar disk at the early stages of its evolution, in addition to the main accretion flux of the gas–dust matter passing through the disk toward the Sun, there was a flux moving in the opposite direction, from the Sun, from the inner hot regions of the circumsolar disk outward to its external regions. There, the nebular matter was mixed with the protosolar matter, which had been precipitating onto the disk from its accretion envelope, mainly onto its edge, during the first million years of its evolution. The currently available package of the experimental data allows us to suppose that it is exactly the mixing of the matter from two regions of the circumsolar disk, within which the P–T conditions significantly differed, that may explain the presence of chemically and isotopically heterogeneous ice–rock bodies in the outer Solar System.
PubDate: 2022-06-01

• Determining the Preliminary Orbit in the Non-Coplanar Case

Abstract: An algorithm for finding a solution for determining a preliminary orbit in the noncoplanar case, when the plane of the desired orbit does not coincide with the plane of motion of an observer, is proposed using a method based on solving a system of transcendental equations for two dimensionless variables. Solutions to the system are found by searching for the minima of the goal function by the Nelder–Mead method using the simplex. As examples, the results of determining the orbit of comet Borisov are given.
PubDate: 2022-06-01

• Relativistic Effect of Geodetic Precession in the Rotation of Dwarf
Planets and Asteroids of the Solar System

Abstract: — Geodetic precession is the most significant relativistic effect in the rotation of celestial bodies. In this work, for the first time, this relativistic effect is determined in the rotation of dwarf planets (Ceres, Pluto and its satellite Charon) and asteroids (Pallas, Vesta, Lutetia, Europa, Ida, Eros, Davida, Gaspra, Steins and Itokawa) of the Solar System with known values of their rotation parameters. Calculations of the values of their geodesic precession are carried out using the method for studying any bodies of the Solar System that have a long-term ephemeris. As a result, geodetic precession values for these celestial bodies were calculated in Euler angles with respect to their own systems. The theoretical values obtained for the geodetic precession of the objects under study can be used for a numerical study of their rotation in the relativistic approximation.
PubDate: 2022-06-01

• Impact-Caused Regolith Reworking within the Polar Regions of the Moon

Abstract: The paper estimates the minimum, mean and maximum thickness of regolith and degree of its impact-caused reworking as a function of depth based on spatial density of small impact craters for the floors of polar craters Shoemaker, Sverdrup and Shackleton and for the landing sites of Luna-16, -17, and -24. Key parameter for these calculations is Dcr, the boundary diameter between the equilibrium and non-equilibrium parts of crater population. It was found to be 80 m for the Luna-24 site and crater Shackleton, 100 m for the Luna-16 and -17 sites, 350 m for crater Sverdrup and 1000 m for crater Shoemaker. The median thicknesses of regolith for these areas were found to be 3,2, 4, 14, and 40 m, respectively. For these areas, the number of the reworking events was found to be 1, 6, 2, 7, and 20 for the 2 m depth, 3, 4, 14 and 40 times for the 1 m depth, 6, 8, 28 and 80 times for the 0,5 m depth, 16, 20, 70, and 200 times for the 0.2 m depth, and 64, 80, 280, and 800 times for the 0.05 m depth. These reworking impacts should mechanically mix the polar regolith and cause multiple local vaporization / condensation of the frozen volatiles leading to their physico-chemical differentiation.
PubDate: 2022-06-01

• Geological Details of the Main Landing Ellipses of Luna-25

Abstract: — The work carried out a comprehensive analysis of engineering and scientific requirements within the main landing ellipses of the Luna-25 expedition. To detail the landing ellipses, data on the conditions of the Earth’s visibility, illumination, critical slopes and cratering, in combination with the geological structure and the presence of hydrogen-containing components in the soil, were considered. Within the ellipses, areas with high, medium, and low engineering constraints on the landing and operation of the descent vehicle were identified. Possible sources of matter accumulated in different locations of the landing ellipses are estimated. These data are important for the interpretation of the soil analysis results at the landing site of the descent vehicle.
PubDate: 2022-06-01

• Selecting a Landing Site for the Luna 27 Spacecraft

Abstract: At present, the task of selecting landing sites for the Luna 27 spacecraft is provided with alarge amount of actual data, often with a higher spatial resolution compared to the data used to select of the Luna 25 landing sites. In addition, more data about the lunar surface with a spatial resolution comparable to the size of a spacecraft can be further obtained using the Luna 26 orbiter. Preliminary estimates of the lunar surface conditions in the south polar region, south of 80° S, for the landing of Luna 27 spacecraft have revealed the need to seriously improve the landing accuracy in comparison with the Luna 25 landing ellipse. The size of such landing ellipse south of 80° S makes a safe landing almost impossible since the surface near the Moon’s south pole does not have a single smooth and illuminated area of that size. Increasing the landing accuracy up to 5 km opens up the possibility of choosing a landing site among six candidates. A further increase in landing accuracy up to 3 km can provide a wide choice among 15 candidate sites, each allowing both a safe landing and the accomplishment of the Luna 27 scientific mission. Finally, with a landing accuracy of about 500 m, one can outline vast areas in the vicinity of the south pole with numerous sites offering favorable conditions both for a safe landing and for carrying out an extensive scientific program.
PubDate: 2022-06-01

• Nonthermal Atmospheric Loss of the Sub-Neptune π Men c Due to
Exothermic Photochemistry

Abstract: We estimated the contribution of reactions of exothermic photochemistry, namely, the dissociation of molecular hydrogen, by extreme UV radiation and the accompanying flux of photoelectrons, to the formation of a fraction of suprathermal atomic hydrogen in the Н2 → Н transition region of the extended upper atmosphere of an exoplanet—the hot sub-Neptune π Men c and the formation of the corresponding escape flux from the atmosphere. We calculate the formation rate and the energy spectrum of hydrogen atoms, which are formed with the excess of kinetic energy when H2 dissociates. With a numerical stochastic model of a hot planetary corona, we study at the molecular level the kinetics and transfer of suprathermal hydrogen atoms in the extended upper atmosphere and calculate the nonthermal escape flux. The escape flux has been estimated as 2.5 × 1012 cm–2 s–1 for moderate activity of the star in the UV-radiation range, from which an upper estimate for the rate of the atmospheric loss caused by the Н2 dissociation processes has been found at 6.7 × 108 g s–1. The calculated value is close to the estimates of the possible atmospheric loss rate obtained in observations of the exoplanet π Men c in the range no higher than 1.0 × 109 g s–1. The rate of the atmospheric loss due to suprathermal hydrogen atoms, which was estimated in calculations for the exoplanet π Men c, may be considered as a mean value, since the calculations were performed for the conditions corresponding to moderate UV-radiation activity of the star and the smallest values of the probabilities for predissociation of the excited electron levels of a Н2 molecule. We recommend this source of suprathermal hydrogen atoms to be included to the current aeronomic models of physical and chemical processes in the upper atmospheres of hot exoplanets.
PubDate: 2022-04-01
DOI: 10.1134/S0038094622020010

• Spectral Signs of Simultaneous Sublimation Activity and the Appearance of
a Dust Exosphere on Eight Asteroids of the Main Belt Near Perihelion

Abstract: — In December 2020, at the 2-m telescope of the Terskol branch of the Institute of Astronomy, we carried out spectrophotometric observations in the range of ~0.36–0.95 μm of nine asteroids of the Main Belt (19 Fortuna, 52 Europa, 102 Miriam, 177 Irma, 203 Pompeja, 250 Bettina, 266 Aline, 379 Huenna, and 383 Janina), which were near perihelia of their orbits with significant eccentricities, in order to determine the effect of maximum subsolar temperatures on them. The study of the reflecance spectra of asteroids showed that the mineralogy of their matter is low-temperature and basically corresponds to the previously established classification (Tholen, 1989; Bus and Binzel, 2002). But in the spectra of eight asteroids (with the exception of 102 Miriam), for the first time, significant deviations were found that go beyond the spectral boundaries of their taxonomic types in the absence of noticeable changes in the spectral transparency of the Earth’s atmosphere at time intervals shorter and longer than the exposure time. Such features can be interpreted as light scattering by a mobile (or inhomogeneous) dusty exosphere that forms near these asteroids near perihelion in the process of ice sublimation at the highest subsolar temperatures. In addition, as follows from the data obtained from the GOES-16 and SOHO satellites, the considered asteroids at the end of November 2020 (10 days before the start of our observations) were affected by a strong solar flare in the X-ray range, and then by a shock wave in solar wind caused by a coronal mass ejection on the Sun, which was quasi-synchronous with the X-ray flare. This probably led to an additional increase in the sublimation activity of the asteroids and manifestations of a derivative dusty exosphere.
PubDate: 2022-04-01
DOI: 10.1134/S0038094622020022

• Transport Characteristics of a Hierarchical Near-Surface Layer of the
Nucleus of Comet 67P/Churyumov–Gerasimenko

Abstract: — In this paper, we develop previous studies that considered a free molecular gas flow through a dust porous mantle of a cometary nucleus. Before, we considered various types of both homogeneous and heterogeneous layers built of nonintersecting spheres, including the layers containing microscopic cracks and inner cavities. At the same time, data from the Rosetta space mission provide convincing evidence that the near-surface layer is composed of porous aggregates rather than homogeneous solids. In this study, we propose models, in which the layer is constructed of porous aggregates formed by ballistic agglomeration. The effective porosity of the model layers is in a range of the values resulting from the analysis of observations of comet Churyumov–Gerasimenko. With the test-particle method, we quantitatively estimated the distribution functions for the free paths, the layer’s permeability, and the other effective kinetic characteristics of sublimation products that passed through a nonisothermal porous layer. In addition, we estimated the volume adsorption of the visible solar light in the near-surface absorbing layer. For all of the considered transport characteristics, we present approximating expressions that may effectively be used in nonstationary thermophysical models of the physics of a cometary nucleus.
PubDate: 2022-04-01
DOI: 10.1134/S0038094622020071

• Coronae of Venus: Geological, Topographic and Morphometric Characteristics

Abstract: — Coronae are large (up to 2500 km in diameter) annular landforms of Venus, the defining structural element of which is the annular framing, consisting of densely packed grooves/ridges. We carried out a detailed photogeological and topographic analysis of 550 coronae and found the following: (1) coronae with younger edging from rift fissures are characterized by a topographic profile with a dominant central dome (class D); this profile probably characterizes the progressive evolutionary stage of the parent diapir. (2) coronae of the transitional type with a frame consisting of groove belts and rift fissures more often have a profile with a central uplift surrounded by one or more concentric depressions (class W); such a profile may correspond to the transition from the progressive to the regressive stage of diapir evolution. (3) Coronae framed by more ancient groove belts or morphologically weakly expressed in relief. They have a profile in the form of a topographic depression (class U), the bottom of which can be complicated by one or more ring uplifts. This profile may be related to the regressive stage of diapir evolution. Apparently, the characteristic topographic profiles of coronae correspond to different stages of their formation and evolution of parental diapirs. The significantly smaller number of D-shaped coronae in comparison with the W and U class coronae indicates a significant decrease in the rate of mantle diapirism at the later stages of the geological history of Venus.
PubDate: 2022-04-01
DOI: 10.1134/S0038094622020046

• Dynamic Evolution of Pairs of Trans-Neptunian Objects

Abstract: A search for pairs of trans-Neptunian objects in close orbits with semimajor axes of more than 30 AU has been performed. Distances in space of Keplerian orbits were estimated using the Kholshevnikov metrics. We revealed 26 pairs of trans-Neptunian objects with metrics less than 0.07 (AU)1/2. Based on nominal orbits, the dynamic evolution of pairs of trans-Neptunian objects in the past over a time interval of 10 million years has been studied numerically. For the pair 2003 QL91—2015 VA173, a study of probabilistic evolution was carried out in the past over a time interval of 10 million years. Estimates of the age of pairs of trans-Neptunian objects obtained by various methods: analysis of low-speed approaches of objects, convergence of orbits, approaches of lines of nodes and apses, give conflicting results. The age of most of the pairs considered exceeds 10 million years.
PubDate: 2022-04-01
DOI: 10.1134/S003809462202006X

• Special Groups of Potentially Hazardous Asteroids

Abstract: — The groups of asteroids which can have approaches to two or more planets have been determined. It is shown that in the phase space of the orbital elements there are regions in which asteroids can be for a long time, potentially hazardous for all the inner planets of the Solar System at the same time. Further study of such objects is necessary, including obtaining new observations.
PubDate: 2022-01-01
DOI: 10.1134/S0038094622010026

• Simulation of Water Vapor Photodissociation during Dust Storm Season on
Mars

Abstract: — Within the framework of this work, using a three-dimensional numerical model of the general circulation of the Martian atmosphere MAOAM (Martian Atmosphere: Observation and Modeling), also known as MPI-MGCM (Max Planck Institute Martian General Circulation Model), we simulated the planet’s hydrological cycle during the 28 and 34 Martian years (MY28 and MY34) dust storm seasons. A quantitative assessment of the photodissociation of water vapor under the influence of solar radiation at the Lyman-alpha wavelength has been carried out. The simulation results are compared with individual profiles obtained with the Atmospheric Chemistry Suite (ACS) spectrometer installed on the ExoMars Trace Gas Orbiter (TGO) spacecraft. The MAOAM model has a spectral dynamical core and successfully predicts the temperature regime of Mars through the use of physical parameterizations that are characteristic of both Earth and Martian models. The hydrodynamic block of the model includes the transfer scheme, microphysics of water vapor and ice, heterogeneous nucleation, sedimentation, photodissociation, and exchange of water with the surface. Studies show the effect of dust storms on both the total water vapor content in the atmosphere and its vertical distribution. More intense pumping of water vapor into the upper atmosphere during dust storms provides more intense photodissociation of water vapor (in some seasons up to 6.5 tons per second in total in the entire atmosphere). The strongest photodissociation is observed at heights of 50 to 80 km for MY34 and 70 to 80 km for MY28. The dissociated water vapor can then potentially become a source of hydrogen dissipation into space, followed by a decrease in the mass of water on the planet.
PubDate: 2022-01-01
DOI: 10.1134/S0038094622010051

• Collocation Integrator Lobbie in Orbital Dynamics Problems

Abstract: — The paper investigates the efficiency of the new collocation integrator Lobbie, presented in (Avdyushev, 2020), in comparison with other integrators widely used in practice, namely, collocation Runge–Kutta, extrapolation Gragg–Bulirsch–Stoer, multistep Adams–Multon–Bashforth integrators, and also with the Everhart integrator, well known in celestial mechanics. The integrators are tested in orbital dynamics problems. In particular, a comparative analysis of efficiency shows that when simulating a complex orbital motion (strongly elliptical or with gravity assist maneuvers), Lobbie excels the other integrators (except Everhart) by several times in performance, and by several orders of magnitude in accuracy. A correct comparison of the efficiency of the Everhart integrator and Lobbie is not possible, since they have no common orders: the former has only odd orders on the Radau spacings, while the latter has only even orders on the Lobatto spacings. Nevertheless, if we compare the efficiency of integrators of adjacent orders, then in the strongly elliptic case the Everhart integrator (with a higher order) is one order of magnitude inferior to Lobbie in accuracy. Another advantage of Lobbie is that it allows solving mixed systems of differential equations of the second and first orders, which, for example, are used in celestial mechanics to study dynamic chaos, as well as to linearize, regularize, and stabilize the equations of motion. To use the Everhart integrator to solve such systems, all second-order equations must be reduced to first-order ones. However, as applied to systems of first-order equations, the efficiency of the Everhart integrator becomes noticeably worse.
PubDate: 2022-01-01
DOI: 10.1134/S0038094622010014

• The δ-Cancrids Meteor Complex

Abstract: — In studying the connections of the δ-Cancrids (DCA) meteor stream, consisting of the northern (NCC) and southern (SCC) branches, with the comet–asteroid complex, the structure of the shower was studied using visual and television observations. According to visual observations, it was found that for meteors with a minimum recorded stellar magnitude of +3m and brighter, the maximum of activity ZHR = 8.6 ± 1.8 is observed at the Sun’s longitude 298.5° ± 1.2°, while the parameter r of the luminosity function during the period of the shower activity varies in the range of 1.5–2.0. For meteors weaker than +3m, the moment of maximum occurs 1.4° later than for brighter meteors. For the orbits of meteors of the NCC and SCC branches, obtained from television observations, the dependence of the values of the semimajor axes and eccentricities on the mass of meteoroids was also revealed. The orbit separation time for the δ-Cancrid meteors in the meteor magnitude range from 0m to +3m due to the nongravitational Poynting–Robertson effect is 22–26 thousand years for the southern branch SCC, and 24–29 thousand years for the northern branch NCC.
PubDate: 2022-01-01
DOI: 10.1134/S0038094622010063

• Rotational Dynamics and Evolution of Planetary Satellites in the Solar and
Exoplanetary Systems

Abstract: In this review we consider the main rotation regimes that are inherent for planetary satellites of the Solar System, satellites of trans-Neptunian objects, and potential satellites of extrasolar planets. Both the findings of classical theoretical studies and the recent conclusions on the observed rotational dynamics of satellites and their long-term dynamical tidal evolution are described. We concentrate on a regime of a satellite’s rotation that is synchronous with its orbital motion and is observed for all major planetary satellites (radius of the figure larger than ~500 km). We also consider irregularly shaped minor satellites (with a figure radius less than ~300 km), rotating regularly and much faster than in the case of synchronous rotation. The regime of chaotic rotation (tumbling) observed for the seventh satellite of Saturn, Hyperion, is analyzed at length. We also discuss the possibility of chaotic rotation of other minor satellites. Results and research prospects for the rotational dynamics of exomoons are presented.
PubDate: 2022-01-01
DOI: 10.1134/S003809462201004X

• Chandrasekhar’s Integral Equilibrium Theorems Modified in the Context of

Abstract: A generalization of Chandrasekhar’s integral theorems on the equilibrium for matter and blackbody radiation in a protostellar gravitating spherically symmetric cloud has been obtained in the context of Kaniadakis nonextensive kappa statistics. The elements of deformed thermodynamics for an ideal gas, the deformed canonical Gibbs distribution, and the effective gravitational constant calculated in the Verlinde formalism are used for this purpose. The deformation parameter $$\kappa$$ measures the so-called degree of nonextensiveness of the cloud system. In addition, modified thermodynamic properties of blackbody radiation are discussed in the context of Kaniadakis statistics, in particular, the κ-analog of Stefan’s law for radiation energy and generalized expressions for the entropy, thermal capacity, and radiation pressure. The presented method of combining these anomalous physical processes provides an alternative to the well-known Chandrasekhar’s integral theorems for spherically symmetric gas configurations in a state of hydrostatic equilibrium, and restores all standard expressions in the limit κ → 0. The approach developed in this study can be used to construct new models of the evolution of nonextensive protostellar objects and stars.
PubDate: 2022-01-01
DOI: 10.1134/S0038094622010038

• The Indo-Russian UV Spectrograph Project for the Chinese Space Station
(SING)

Abstract: —The ultraviolet wavelength range (90–300 nm) is one of the most important parts of the electromagnetic spectrum for astrophysicists. The success of the GALEX and ASTROSAT/UVIT missions has given a new view on the ultraviolet sky with unprecedented detail of extended objects, such as planetary nebulae or supernova remnants. Direct images of the sky allow us to track the morphology of such objects, but provide very limited information about their physical conditions: temperature, density, and radiation fields. Spectroscopic observations make it possible to study local physical conditions, but usually only at one point in an extended nebula. Our proposed long-slit spectrograph (SING, Spectroscopic Investigation of Nebular Gas) will allow tracking emission lines across the entire spatially extended nebulae in the wavelength range of 140–270 nm, which is the key to understanding their dynamics and evolution. The spectrograph will operate onboard the Chinese space station. The article describes the scientific tasks for which this unique device is created, its main characteristics and preliminary design.
PubDate: 2021-12-01
DOI: 10.1134/S0038094621070169

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