{"title":"Modification of Gravitational Instability Criteria for Astrophysical Disks within Nonadditive Thermodynamics","authors":"","doi":"10.1134/s0038094623070109","DOIUrl":null,"url":null,"abstract":"<span> <h3>Abstract</h3> <p>In contrast to several classical studies, in which gravitational instability criteria for astrophysical disks are derived within traditional hydrodynamics or kinetics, it is proposed to consider the set of loose gas–dust clusters of an accretion protoplanetary disk as a special type of continuous medium, i.e., a fractal medium whose phase velocity space contains points and areas not filled by its components. Within the Tsallis formalism of nonadditive statistics (thermodynamics), intended to describe the behavior of anomalous systems, i.e., systems with a strong gravitational interaction of its individual parts and the fractal nature of the phase space, linearized equations are obtained for oscillations of a solid-state rotating disk on the basis of modified Navier–Stokes hydrodynamic equations (the so-called <em>q</em>-hydrodynamics equations) and in view of dissipative effects, and a derivation is given of the dispersion equation in the WKB approximation. An analysis is conducted of axisymmetric oscillations of a differentially rotating astrophysical gas–dust space object to obtain modified Jeans and Toomre gravitational instability criteria for disks with a fractal structure.</p> </span>","PeriodicalId":778,"journal":{"name":"Solar System Research","volume":null,"pages":null},"PeriodicalIF":0.6000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Solar System Research","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1134/s0038094623070109","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
In contrast to several classical studies, in which gravitational instability criteria for astrophysical disks are derived within traditional hydrodynamics or kinetics, it is proposed to consider the set of loose gas–dust clusters of an accretion protoplanetary disk as a special type of continuous medium, i.e., a fractal medium whose phase velocity space contains points and areas not filled by its components. Within the Tsallis formalism of nonadditive statistics (thermodynamics), intended to describe the behavior of anomalous systems, i.e., systems with a strong gravitational interaction of its individual parts and the fractal nature of the phase space, linearized equations are obtained for oscillations of a solid-state rotating disk on the basis of modified Navier–Stokes hydrodynamic equations (the so-called q-hydrodynamics equations) and in view of dissipative effects, and a derivation is given of the dispersion equation in the WKB approximation. An analysis is conducted of axisymmetric oscillations of a differentially rotating astrophysical gas–dust space object to obtain modified Jeans and Toomre gravitational instability criteria for disks with a fractal structure.
期刊介绍：
Solar System Research publishes articles concerning the bodies of the Solar System, i.e., planets and their satellites, asteroids, comets, meteoric substances, and cosmic dust. The articles consider physics, dynamics and composition of these bodies, and techniques of their exploration. The journal addresses the problems of comparative planetology, physics of the planetary atmospheres and interiors, cosmochemistry, as well as planetary plasma environment and heliosphere, specifically those related to solar-planetary interactions. Attention is paid to studies of exoplanets and complex problems of the origin and evolution of planetary systems including the solar system, based on the results of astronomical observations, laboratory studies of meteorites, relevant theoretical approaches and mathematical modeling. Alongside with the original results of experimental and theoretical studies, the journal publishes scientific reviews in the field of planetary exploration, and notes on observational results.
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