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The role of the magnetodisk in the Jupiter's Magnetosphere

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### TheroleofthemagnetodiskintheJupiter'sMagnetosphere

### Thank you !!!

Igor I. Alexeev

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

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

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

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

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

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

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

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 generatorLanday and Lifshitz, 1959

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

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

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

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

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

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

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

Magnetospheric parameters

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

Solar wind potential prop and unipolar inductor

Open Sun flux

ΦSpc= 499 TWb

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

“Sling” model by magnetodisk

Slinger from the

Balearic Islands

with the sling

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

17

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

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

2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow

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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