Neutral cloud theory of the Jovian nebula: Anomalous ionization effect of superthermal electrons

Abstract

view Abstract Citations (35) References (61) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Neutral Cloud Theory of the Jovian Nebula: Anomalous Ionization Effect of Superthermal Electrons Barbosa, D. D. Abstract The standard model of the Jovian nebula postulates that its particle source is the extended cloud of neutral sulfur and oxygen atoms that escape from the satellite Io and become ionized through electron impact from the corotating plasma. Its energy source is the gyroenergy acquired by newly formed pickup ions as they are swept up to corotation velocity by the planetary magnetic field. Elastic collisions between plasma ions and electrons cool the ions and heat the electrons, while inelastic collisions cool the electrons and excite the ions to radiate intense line emission, which is the primary energy-loss mechanism for the plasma. This neutral cloud theory of the Io plasma torus, as it has come to be known, has been the subject of recent critcism which asserts that the theory cannot account for the observed charge state of the plasma which features O(+) and S(2+) as the dominant ions. It is shown in this work that the inclusion of a small population of super-thermal electrons is required to achieve the correct ion partitioning among various charge states. It is also argued that the anomalous ionization effect of the superthermal electrons is responsible for the overall spatial bifurcation of the nebula into a hot multiply charged plasma region outside of 5.7 Jovian radii and a cool singly ionized plasma inside this distance. Publication: The Astrophysical Journal Pub Date: July 1994 DOI: 10.1086/174413 Bibcode: 1994ApJ...430..376B Keywords: Astronomical Models; Hot Electrons; Interplanetary Medium; Ionization; Jupiter (Planet); Neutral Atoms; Plasma Clouds; Space Plasmas; Electron Acceleration; Io; Oxygen Atoms; Plasma Waves; Sulfur; Toruses; Astrophysics; ACCELERATION OF PARTICLES; PLANETS AND SATELLITES: INDIVIDUAL JUPITER; RADIATION MECHANISMS: MISCELLANEOUS full text sources ADS |