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The role of the magnetodisk in the Jupiter's Magnetosphere

The role of the magnetodisk in the Jupiter's Magnetosphere. Igor I. Alexeev. Content. Introduction. Plasma spherical outflow in dipole field? Plasma beta in the Jupiter magnetosphere. Sling model of the plasma magnetodisk.

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The role of the magnetodisk in the Jupiter's Magnetosphere

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  1. TheroleofthemagnetodiskintheJupiter'sMagnetosphere Igor I. Alexeev 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  2. Content • Introduction. Plasma spherical outflow in dipole field? • Plasma beta in the Jupiter magnetosphere. Sling model of the plasma magnetodisk. • The Jupiter magnetospheric magnetic field dependence on radial distance R as measured by Ulysses and by Galileo. • Energetic ions 50 keV – 500 MeV in the magnetodisk region. Particles acceleration at the disk crossing • Comparison of the Mercury, Earth, Jupiter, and Saturn magnetosphere • Conclusions 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  3. Black streamlines represent the final configuration of the magnetic field. Meridional cuts of the steady-state configurations for simulations S03. The white line is the Alfv´en surface. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  4. The transition from dipole like to stretched tail-like field lines. Nearest Earth tail edge (e.g. Lui et al., 1992). The carton is based on data by AMPTE CCE Magnetic Field Experiment 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  5. The dependences of the ratios and to module magnetic field as functions of the distance are shown. These functions demonstrated that sharp (at about 1000 km thickness) transition layer from dipole northward magnetic field to earthward magnetic field directions. (Alexeev, 2008) 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  6. TheJovian magnetospheric magneticfielddependendonradialdistanceR as measuredbyUlysses [Cowley etal., 1996] and model Alexeev Belenkaya 2005. R-2 power-law, solid curve R-3 jovian dipole powerlaw, dotted curve. All model curves were normalized on measured field strength at 20 Rj - 62.2 nT. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  7. Relative intensity versus pitch angle versus time and position for 15- to 29-keV electron data as generated and reported by Toma´s et al. [2004a, 2004b] using data from the Galileo EPD instrument 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  8. Schematic of the relationship between observed equatorial electron field-aligned enhancements reported by Toma´s et al. [2004a, 2004b] and the circuit of electric currents that connects Jupiter’s middle magnetosphere to the auroral ionosphere. The auroral circuit figure is based on concepts of Hill [1979] and Vasyliunas [1983] as replotted by Mauk et al. [2002]. It is understood that the shape of the field lines in the actual Jovian system are substantially stretched away from the dipolar configuration. Unipolar jovian generator Landay and Lifshitz, 1959 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  9. Mauk, et al., 2004, Energetic ion and neutral gas interactions in Jupiter’s magnetosphere, JGR, 109 Energetic ion pressure distributions. (a) Comparison of the >50-keV contributions derived here (red triangles) with the <52-keV contributions derived for one particular Galileo orbit (G8) by Frank et al. [2002] for radial positions 10 RJ (solid blue squares), and the plasma contributions for radial positions <10 RJ calculated by Mauk et al. [1996] using the spectral fits of 6-keV ion data from Voyager provided by Bagenal [1994] (open blue diamonds). Figure 5a also compares the total summed ion Pressures (green diamonds) with the magnetic lobe magnetic pressures provided by Frank et al. [2002], again for the one particular Galileo orbit (G8), and that obtained using the magnetic field model of Khurana [1997] as evaluated 10 in latitude away from the minimum magnetic field strength position. (b) The minimum-B plasma ‘‘beta’’ parameter, derived using the >50-keV ion pressures and the total ion pressures, both normalized with the magnetic pressures at the positions of the minimum magnetic field strength as determined using the field model of Khurana [1997] for the r < 30 RJ positions, and as measured by Galileo for the two most radially distant positions. The Khurana [1997] model underpredicts the field strengths for the particular neutral sheet crossings at 39 RJ and 46 RJ, yielding much higher values of beta than those shown in the figure. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  10. Went, D. R., M. G. Kivelson, N. Achilleos, C. S. Arridge, and M. K. Dougherty (2011), Outer magnetosphericstructure: Jupiter and Saturn compared, J. Geophys. Res., 116, A04224, doi:10.1029/2010JA016045. Ulysses observations in the Jovian magnetosphere. (a) Jovian System III magnetic field components (BR, red; B, blue or white; B, green) and ±∣B∣ (black). (b) Normalized poloidal field components (∣B∣/∣B∣, blue or white; ∣BR∣/∣B∣, red). (c) Angle INT between the observed magnetic field, BOBS, and the internal magnetic field, BINT. Horizontal dashed lines denote the critical magnetodisk angles of 50° and 180 − 50 = 130°. (d) Thirty‐minute normalized magnetic field RMS fluctuation. (e) SWOOPS thermal electron density (blue or white) and temperature (red). Vertical dashed lines denote local minima in absolute magnetic latitude, ∣lM∣,which beyond 50 RJ corresponds to lM = 0°. The inner magnetosphere (blue), magnetodisk (yellow), transition region (white), cushion region (green), boundary layers (cyan), Magnetopause crossings (red), and magnetosheath (grey) are shaded. The radial distance, planetocentric latitude, and local time of the spacecraft are shown along the x axis. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  11. Equation (1) describes the first‐order balance between the magnetic curvature force (left), pressure gradient force (right) and centrifugal force (far right). Here RC is the local radius of curvature of the field, B2/2μ0 is the magnetic pressure, P is the plasma pressure (assumed to be isotropic), Ni is the number density of ions , mean dmi are the electron and mean ion masses, respectively, Ω is the angular frequency of plasma rotation and r is the perpendicular distance from the spin axis of the planet about which the plasma rotates. The unit vector ^n points in the direction of the outward normal to the field line. According to this equation, higher‐density plasmas will tend to “stretch out” the magnetic field (decreasing the radius of curvature in order to increase the stabilizing tension force) whereas lower‐density plasmas, at a given r and w, can be successfully constrained by a less stretched configuration. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  12. Khurana, K. K., and H. K. Schwarzl (2005), Global structure of Jupiter’s magnetospheric current sheet, J. Geophys. Res., 110, A07227 An example of magnetic field data collected by Galileo in the dawn sector. Also marked are the N!S crossings (solid lines) and the S!N crossings (dashed lines) identified by the software used in this work. Please note that the y axis scale for the Bj panel is different from the other three panels. Half thickness of the current sheet is 2.5 RJ 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  13. Observed ratio Bf/(rBr) in the Jovian magnetosphere computed from data obtained from all six of the spacecraft that have visited Jupiter. The magnetic field observations from the postmidnight (dawn) sector (radial distance 40–85 RJ) of Jupiter’s magnetotail. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  14. Noon-midnight meridian plane. Magnetodisk plasma preserves the reconnection of southern and northern magnetic fluxes across the equatorial plane and transfers it to the outer magnetosphere • Meff=Mdip+Mdisk • Meff= 4 Mdip 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  15. Magnetospheric parameters 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  16. Solar wind potential prop and unipolar inductor Open Sun flux ΦSpc= 499 TWb 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  17. “Sling” model by magnetodisk Slinger from the Balearic Islands with the sling 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow 17

  18. JupiterNoon-midnight meridian plane Magnetodisk plasma preserve the magnetic flux reconnectionacross the equatorial plane Meff=Mdip+Mdisk, Meff= 4 Mdip 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow 18

  19. Conclusions • Plasma outflow at Alfvenic radius formed the magnetodisk • Jupiter’s magnetosphere is most interesting object. It is a biggest in Solar System. The jovian magnetodisk doubled the magnetospheric size. • Acceleration of the particle at the disk sheet crossing is the main source of the energetic ions. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow 19

  20. Thank you !!! 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

  21. Spectra, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances of 6 to 46 Jupiter radii (RJ), as revealed by analysis of the Galileo Energetic Particle Detector data. 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

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