Pub Date : 2024-06-17DOI: 10.3103/s0884591324030048
A. S. Guliyev, R. A. Guliyev
Abstract
Statistical dependences of orbit parameters in four groups of sungrazing comets are studied. It is shown that the perihelia of comets of the Kreutz family are clustered around two planes (great circles of the celestial sphere). Numerical data on the observed bifurcation of perihelion distribution are provided. One of the planes basically coincides with the plane obtained by averaging orbit parameters Ω and i. The second plane with parameters Ωp = 77.7° and ip = 266.1° has an inclination of approximately 64° relative to the first plane. The distant nodes of cometary orbits relative to this plane are clustered at a distance of approximately 2 a.u. On the basis of the above, one of the authors hypothesizes that the comet group originates from the collision of a large comet with a meteoroid stream. This study examines some counterarguments expressed regarding this hypothesis. It is shown, based on a particular case, that the assumptions about the concentration of comet perihelia near one point and along two circles of the celestial sphere are quite compatible. The distribution of orbit inclinations relative to this plane is analyzed and a sharp maximum near 90° is noted. The maximum indicates that the parent body experienced lateral impacts of meteoroid bodies in all probability, which caused defragmentation of the former. New confirmations of the suggested hypothesis about the presence of another group of sungrazers have been found. It is assumed that the correlation dependence between the values of the perihelion parameters and ascending nodes of cometary orbits is of an evolutionary nature and is related to the group formation process. New relationships that concern the Meyer, Kracht, and Marsden groups are introduced. In particular, the authors have calculated the planes near which the cometary perihelia of these groups are concentrated. The example of the Meyer group illustrates the bifurcation of perihelia.
{"title":"On the Origin of Sungrazing Comet Groups","authors":"A. S. Guliyev, R. A. Guliyev","doi":"10.3103/s0884591324030048","DOIUrl":"https://doi.org/10.3103/s0884591324030048","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Statistical dependences of orbit parameters in four groups of sungrazing comets are studied. It is shown that the perihelia of comets of the Kreutz family are clustered around two planes (great circles of the celestial sphere). Numerical data on the observed bifurcation of perihelion distribution are provided. One of the planes basically coincides with the plane obtained by averaging orbit parameters Ω and <i>i</i>. The second plane with parameters Ω<sub><i>p</i></sub> = 77.7° and <i>i</i><sub><i>p</i></sub> = 266.1° has an inclination of approximately 64° relative to the first plane. The distant nodes of cometary orbits relative to this plane are clustered at a distance of approximately 2 a.u. On the basis of the above, one of the authors hypothesizes that the comet group originates from the collision of a large comet with a meteoroid stream. This study examines some counterarguments expressed regarding this hypothesis. It is shown, based on a particular case, that the assumptions about the concentration of comet perihelia near one point and along two circles of the celestial sphere are quite compatible. The distribution of orbit inclinations relative to this plane is analyzed and a sharp maximum near 90° is noted. The maximum indicates that the parent body experienced lateral impacts of meteoroid bodies in all probability, which caused defragmentation of the former. New confirmations of the suggested hypothesis about the presence of another group of sungrazers have been found. It is assumed that the correlation dependence between the values of the perihelion parameters and ascending nodes of cometary orbits is of an evolutionary nature and is related to the group formation process. New relationships that concern the Meyer, Kracht, and Marsden groups are introduced. In particular, the authors have calculated the planes near which the cometary perihelia of these groups are concentrated. The example of the Meyer group illustrates the bifurcation of perihelia.</p>","PeriodicalId":681,"journal":{"name":"Kinematics and Physics of Celestial Bodies","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506939","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}
Pub Date : 2024-06-17DOI: 10.3103/s088459132403005x
V. N. Krivodubskij
Abstract
According to classical magnetohydrodynamics, the magnetic fields on the Sun are characterized by huge theoretically calculated time intervals of their ohmic dissipation due to the high inductance caused by the large size of the fields and the high gas kinetic electrical conductivity of the plasma. This is in striking contrast to the observed rapid changes in the structure of solar magnetism. To solve such a contradiction, it becomes relevant to search for new methods of studying magnetized plasma. Research efforts to consider turbulent motions in the plasma ended with the creation of macroscopic magnetohydrodynamics (MHD), within which substantial decreases in the electrical conductivity and magnetic permeability leading to a decrease in the calculated time of reconstruction of global magnetic fields are found. This study aims at calculating the coefficients of turbulent electrical conductivity and turbulent magnetic permeability of the solar plasma and analyzing changes in the spatiotemporal evolution of the global magnetism of the Sun considering these parameters. Macroscopic MHD methods are used for studying the behavior of global electromagnetic fields and hydrodynamic motions in turbulent plasma. For models of the photosphere and convection zone of the Sun, the distributions of the following parameters along the solar radius are calculated: coefficients of kinematic (ν), magnetic (νm), and turbulent (νT) viscosities; hydrodynamic (Re) and magnetic (Rm) Reynolds numbers; gas kinetic (σ) and turbulent (σT) electrical conductivities; and turbulent magnetic permeability μT. The theoretically calculated parameters have the following values: ν = 0.2–10 cm2/s; νm = 6 × 108–8 × 102 cm2/s; νT = 1011–1013 cm2/s; Re = 5 × 1011–5 × 1013; Rm = 104–1010; σ = 1011–4 × 1016 CGS; σT = 109–4 × 1011 CGS; μT = 10–2–4 × 10–5. It is essential that σT( ll ) σ and μT( ll ) 1. Calculated turbulent magnetic diffusion DT = c2/4πσTμT turned out to be four to nine orders of magnitude higher than magnetic viscosity coefficient νm = c2/4πσ, which is responsible for the ohmic dissipation of magnetic fields. As a result, it becomes possible to theoretically explain the observed rapid reconstruction of magnetism on the Sun. We have revealed the radial inhomogeneity of turbulent viscosity νT and condition μT( ll ) 1, which are indicative of the strong macroscopic diamagnetism of the solar plasma. In the lower part of the solar convection zone, the latter performs the role of negative
{"title":"Electrical Conductivity and Magnetic Permeability of Magnetohydrodynamic Turbulent Plasma of the Sun","authors":"V. N. Krivodubskij","doi":"10.3103/s088459132403005x","DOIUrl":"https://doi.org/10.3103/s088459132403005x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>According to classical magnetohydrodynamics, the magnetic fields on the Sun are characterized by huge theoretically calculated time intervals of their ohmic dissipation due to the high inductance caused by the large size of the fields and the high gas kinetic electrical conductivity of the plasma. This is in striking contrast to the observed rapid changes in the structure of solar magnetism. To solve such a contradiction, it becomes relevant to search for new methods of studying magnetized plasma. Research efforts to consider turbulent motions in the plasma ended with the creation of macroscopic magnetohydrodynamics (MHD), within which substantial decreases in the electrical conductivity and magnetic permeability leading to a decrease in the calculated time of reconstruction of global magnetic fields are found. This study aims at calculating the coefficients of turbulent electrical conductivity and turbulent magnetic permeability of the solar plasma and analyzing changes in the spatiotemporal evolution of the global magnetism of the Sun considering these parameters. Macroscopic MHD methods are used for studying the behavior of global electromagnetic fields and hydrodynamic motions in turbulent plasma. For models of the photosphere and convection zone of the Sun, the distributions of the following parameters along the solar radius are calculated: coefficients of kinematic (ν), magnetic (ν<sub>m</sub>), and turbulent (ν<sub>T</sub>) viscosities; hydrodynamic (Re) and magnetic (Rm) Reynolds numbers; gas kinetic (σ) and turbulent (σ<sub>T</sub>) electrical conductivities; and turbulent magnetic permeability μ<sub>T</sub>. The theoretically calculated parameters have the following values: ν = 0.2–10 cm<sup>2</sup>/s; ν<sub>m</sub> = 6 × 10<sup>8</sup>–8 × 10<sup>2</sup> cm<sup>2</sup>/s; ν<sub>T</sub> = 10<sup>11</sup>–10<sup>13</sup> cm<sup>2</sup>/s; Re = 5 × 10<sup>11</sup>–5 × 10<sup>13</sup>; Rm = 10<sup>4</sup>–10<sup>10</sup>; σ = 10<sup>11</sup>–4 × 10<sup>16</sup> CGS; σ<sub>T</sub> = 10<sup>9</sup>–4 × 10<sup>11</sup> CGS; μ<sub>T</sub> = 10<sup>–2</sup>–4 × 10<sup>–5</sup>. It is essential that σ<sub>T</sub> <span>( ll )</span> σ and μ<sub>T</sub> <span>( ll )</span> 1. Calculated turbulent magnetic diffusion <i>D</i><sub>T</sub> = <i>c</i><sup>2</sup>/4πσ<sub>T</sub>μ<sub>T</sub> turned out to be four to nine orders of magnitude higher than magnetic viscosity coefficient ν<sub>m</sub> = <i>c</i><sup>2</sup>/4πσ, which is responsible for the ohmic dissipation of magnetic fields. As a result, it becomes possible to theoretically explain the observed rapid reconstruction of magnetism on the Sun. We have revealed the radial inhomogeneity of turbulent viscosity ν<sub>T</sub> and condition μ<sub>T</sub> <span>( ll )</span> 1, which are indicative of the strong macroscopic diamagnetism of the solar plasma. In the lower part of the solar convection zone, the latter performs the role of negative ","PeriodicalId":681,"journal":{"name":"Kinematics and Physics of Celestial Bodies","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506938","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}