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The role of the The role of the magnetodisk in the magnetodisk in the
Jupiter's MagnetosphereJupiter's Magnetosphere
Igor I. AlexeevIgor I. Alexeev
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 11
ContentContent
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, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 22
Black streamlines represent the final configuration of the magnetic Black streamlines represent the final configuration of the magnetic
fieldfield. . Meridional cuts of the steady-state configurations for Meridional cuts of the steady-state configurations for
simulations S03simulations S03. The white line is the Alfv´. The white line is the Alfv´en surface.en surface.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 33
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 44
The transition from dipole like The transition from dipole like to stretched tail-like field lines.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
The dependences of the The dependences of the ratios and to module ratios and to module magnetic field as functions magnetic field as functions of the distance are shown. of the distance are shown. These functions These functions demonstrated that sharp (at demonstrated that sharp (at about 1000 km thickness) about 1000 km thickness) transition layer from dipole transition layer from dipole northward magnetic field to northward magnetic field to earthward magnetic field earthward magnetic field directions. (Alexeev, 2008)directions. (Alexeev, 2008)
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 55
TThe he JJovian magnetospheric magnetic ovian magnetospheric magnetic fifield eld dependend on radial distance dependend on radial distance R asR as mmeasured byeasured by Ulysses Ulysses [[Cowley et al., 1996Cowley et al., 1996]] and model Alexeev Belenkaya 2005.and model Alexeev Belenkaya 2005.
RR-2-2 power-law, solid curve power-law, solid curve
RR-3-3 jovian dipole powerlaw, jovian dipole powerlaw,
dotted curve. dotted curve. All model curveAll model curvess w were ere normalized normalized
on measured on measured fifield strength at eld strength at
20 Rj 20 Rj -- 62.2 62.2 nT. nT.
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2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 77
Relative intensity versus pitch angle versus time Relative intensity versus pitch angle versus time and position for 15- to 29-keV electron data as and position for 15- to 29-keV electron data as generated and reported by Toma´s et al. generated and reported by Toma´s et al. [2004a, 2004b] using data from the Galileo EPD [2004a, 2004b] using data from the Galileo EPD instrumentinstrument
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 88
Unipolar jovian generatorUnipolar jovian generator Schematic of the relationship Schematic of the relationship between observed equatorial between observed equatorial electron field-aligned electron field-aligned enhancements reported by Toma´s enhancements reported by Toma´s et al. [2004a, 2004b] and the et al. [2004a, 2004b] and the circuit of electric currents that circuit of electric currents that connects Jupiter’s middle connects Jupiter’s middle magnetosphere to the auroral magnetosphere to the auroral ionosphere. The auroral circuit ionosphere. The auroral circuit figure is based on concepts of Hill figure is based on concepts of Hill [1979] and Vasyliunas [1983] as [1979] and Vasyliunas [1983] as replotted by Mauk et al. [2002]. It replotted by Mauk et al. [2002]. It is understood that the shape of the is understood that the shape of the field lines in the actual Jovian field lines in the actual Jovian system are substantially stretched system are substantially stretched away from the dipolar away from the dipolar
configuration.configuration.
Landay and Lifshitz, 1959
Mauk, et al., 2004, Energetic Mauk, et al., 2004, Energetic ion and neutral gas ion and neutral gas interactions in interactions in Jupiter’s magnetosphere, Jupiter’s magnetosphere, JGR, 109JGR, 109
Energetic ion pressure distributions. (a) Comparison of Energetic ion pressure distributions. (a) Comparison of
the >50-keV contributions derived here (red triangles) the >50-keV contributions derived here (red triangles)
with the <52-keV contributions derived for onewith the <52-keV contributions derived for one
particular Galileo orbit (G8) by Frank et al. [2002] forparticular Galileo orbit (G8) by Frank et al. [2002] for
radial positions 10 RJ (solid blue squares), and the plasmaradial positions 10 RJ (solid blue squares), and the plasma
contributions for radial positions <10 RJ calculated by contributions for radial positions <10 RJ calculated by
Mauk et al. [1996] using the spectral fits of 6-keV ion Mauk et al. [1996] using the spectral fits of 6-keV ion
data from Voyager provided by Bagenal [1994] (open data from Voyager provided by Bagenal [1994] (open blue blue
diamonds). Figure 5a also compares the total summed diamonds). Figure 5a also compares the total summed ion ion
Pressures (green diamonds) with the magnetic lobe Pressures (green diamonds) with the magnetic lobe
magnetic pressures provided by Frank et al. [2002], again magnetic pressures provided by Frank et al. [2002], again
for the one particular Galileo orbit (G8), and that for the one particular Galileo orbit (G8), and that
obtained using the magnetic field model of Khurana obtained using the magnetic field model of Khurana
[1997] as evaluated 10 in latitude away from the [1997] as evaluated 10 in latitude away from the minimum minimum
magnetic field strength position. (b) The minimum-B magnetic field strength position. (b) The minimum-B
plasma ‘‘beta’’ parameter, derived using the >50-keV ion plasma ‘‘beta’’ parameter, derived using the >50-keV ion
pressures and the total ion pressures, both normalized pressures and the total ion pressures, both normalized
with the magnetic pressures at the positions of thewith the magnetic pressures at the positions of the
minimum magnetic field strength as determined using minimum magnetic field strength as determined using the the
field model of Khurana [1997] for the r < 30 RJ field model of Khurana [1997] for the r < 30 RJ
positions, and as measured by Galileo for the two most positions, and as measured by Galileo for the two most
radially distant positions. The Khurana [1997] model radially distant positions. The Khurana [1997] model
underpredicts the field strengths for the particular underpredicts the field strengths for the particular
neutral sheet crossings at 39 RJ and 46 RJ, yielding neutral sheet crossings at 39 RJ and 46 RJ, yielding
much higher values of beta than those shown in the much higher values of beta than those shown in the
figure.figure.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 99
Went, D. R., M. G. Kivelson, N. Achilleos, C. S. Went, D. R., M. G. Kivelson, N. Achilleos, C. S. Arridge, and M. K. Dougherty (2011), Outer Arridge, and M. K. Dougherty (2011), Outer
magnetosphericmagnetosphericstructure: Jupiter and Saturn compared, structure: Jupiter and Saturn compared, J. Geophys. J. Geophys.
Res., 116, A04224, doi:10.1029/2010JA016045.Res., 116, A04224, doi:10.1029/2010JA016045.Ulysses observations in the Jovian magnetosphere. Ulysses observations in the Jovian magnetosphere.
(a) (a)
Jovian System III magnetic field components (BR, Jovian System III magnetic field components (BR,
red; B, blue or white; B, green) and ±∣B∣ (black). (b) red; B, blue or white; B, green) and ±∣B∣ (black). (b)
Normalized poloidal field components (∣B∣/∣B∣, blue Normalized poloidal field components (∣B∣/∣B∣, blue
or white; ∣BR∣/∣B∣, red). (c) Angle INT between the or white; ∣BR∣/∣B∣, red). (c) Angle INT between the
observed magnetic field, BOBS, and the internal observed magnetic field, BOBS, and the internal
magnetic field, BINT. Horizontal dashed lines denote magnetic field, BINT. Horizontal dashed lines denote
the critical magnetodisk angles of 50° and 180 − 50 the critical magnetodisk angles of 50° and 180 − 50 = =
130°. (d) Thirty‐minute normalized magnetic field 130°. (d) Thirty‐minute normalized magnetic field
RMS fluctuation. (e) SWOOPS thermal electron RMS fluctuation. (e) SWOOPS thermal electron
density (blue or white) and temperature (red). density (blue or white) and temperature (red).
Vertical dashed lines denote local minima in absoluteVertical dashed lines denote local minima in absolute
magnetic latitude, ∣lM∣,which beyond 50 RJ magnetic latitude, ∣lM∣,which beyond 50 RJ
corresponds to lM = 0°. The inner magnetosphere corresponds to lM = 0°. The inner magnetosphere
(blue), magnetodisk (yellow), transition region (blue), magnetodisk (yellow), transition region (white), (white),
cushion region (green), boundary layers (cyan), cushion region (green), boundary layers (cyan),
Magnetopause crossings (red), and magnetosheath Magnetopause crossings (red), and magnetosheath
(grey) are shaded. The radial distance, planetocentric (grey) are shaded. The radial distance, planetocentric
latitude, and local time of the spacecraft are shown latitude, and local time of the spacecraft are shown
along the x axis.along the x axis.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1010
Equation (1) describes the first‐order balance between the magnetic Equation (1) describes the first‐order balance between the magnetic
curvature force (left), pressure gradient force (right) and centrifugal curvature force (left), pressure gradient force (right) and centrifugal
force (far right). Here Rforce (far right). Here RCC is the local radius of curvature of the field, is the local radius of curvature of the field,
BB22/2/2μμ00 is the magnetic pressure, P is the plasma pressure (assumed to is the magnetic pressure, P is the plasma pressure (assumed to
be isotropic), Ni is the number density of ions , mean dmi are the be isotropic), Ni is the number density of ions , mean dmi are the electron electron
and mean ion masses, respectively, and mean ion masses, respectively, ΩΩ is the angular frequency of plasma is the angular frequency of plasma
rotation and r is the perpendicular distance from the spin axis of the 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 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 direction of the outward normal to the field line. According to this
equation, higher‐density plasmas will tend to “stretch out” the magnetic equation, higher‐density plasmas will tend to “stretch out” the magnetic
field (decreasing the radius of curvature in order to increase the field (decreasing the radius of curvature in order to increase the
stabilizing tension force) whereas lower‐density plasmas, stabilizing tension force) whereas lower‐density plasmas, at a given r and at a given r and
w, can be successfully constrained by a less stretched configuration.w, can be successfully constrained by a less stretched configuration.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1111
Khurana, K. K., and H. K. Schwarzl (2005), Khurana, K. K., and H. K. Schwarzl (2005), Global structure of Jupiter’s magnetospheric Global structure of Jupiter’s magnetospheric current sheet, J. Geophys. Res., 110, A07227current sheet, J. Geophys. Res., 110, A07227
An example of magnetic field An example of magnetic field
data collected by Galileo in the data collected by Galileo in the
dawn sector. Also marked aredawn sector. Also marked are
the N!S crossings (solid lines) the N!S crossings (solid lines)
and the S!N crossings (dashed and the S!N crossings (dashed
lines) identified by the software lines) identified by the software
used in this work. Please note that used in this work. Please note that
the y axis scale for the Bj panel is the y axis scale for the Bj panel is
different from the other three different from the other three
panels. Hpanels. Half thickness of the alf thickness of the current current
sheet is 2.5 Rsheet is 2.5 RJJ
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2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1313
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.
Noon-midnight meridian plane.Noon-midnight meridian plane. Magnetodisk plasma preserves the Magnetodisk plasma preserves the
reconnection of reconnection of
southern and northern magnetic fluxes across southern and northern magnetic fluxes across the the
equatorial plane and transfers it to the outer equatorial plane and transfers it to the outer
magnetospheremagnetosphere
MMeffeff=M=Mdipdip+M+Mdiskdisk
MMeffeff= 4 M= 4 Mdipdip
23.0
8.39
sw
Js p
RR
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1414
Magnetospheric parametersMagnetospheric parametersRo
au
Bm
nT
Mp
nT·m3
R1
106 km
Icf
MA
θpc
degs
Mercury 0.38
196. 2.84·1012
0.003 0.53 55
Earth 1.0 74.5 7.86·1015
0.069 4.09 20
Jupiter 5.2 14.3 1.53·1020
5.72 65.0 15
Saturn 9.5 7.8 4.6·1018 1.32 8.36 13
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1515
Solar wind potential prop Solar wind potential prop and unipolar inductorand unipolar inductor
Open Sun fluxOpen Sun flux
ΦΦSpcSpc= 499 TWb= 499 TWb
Ro
au
BIMF
nTΩp104 ra/s
ΔΦrot
MB
ΔΦsw
MBΔΦrpc
MB
θpc
degs
.38 9.3 0.01 1.4 B
.005 1 B 55
1.0 3.5 0.73 0.09 .05 0.01 20
5.2 .66 1.76 367. .72 24.6 15
9.5 .37 1.61 12.2 .09 0.6 13
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow
1616
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1717
““Sling” model by Sling” model by magnetodisk magnetodisk
SSlinger from the linger from the Balearic Islands Balearic Islands with the sling with the sling 1717
JupiterJupiterNoon-midnight meridian planeNoon-midnight meridian plane
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 18181818
3~ RB
2~ RB
23.0
8.39
sw
Js p
RR
Magnetodisk plasma preserve the magnetic flux Magnetodisk plasma preserve the magnetic flux reconnectionreconnection across the equatorial plane across the equatorial plane MMeff=M=Mdip+M+Mdisk, , MMeff= 4 M= 4 Mdip
1919
ConclusionsConclusions Plasma outflow at Alfvenic radius Plasma outflow at Alfvenic radius
formed the magnetodiskformed the magnetodisk Jupiter’s magnetosphere is most Jupiter’s magnetosphere is most
interesting object. It is a biggest in interesting object. It is a biggest in Solar System. The jovian Solar System. The jovian magnetodisk doubled the magnetodisk doubled the magnetospheric size. magnetospheric size.
Acceleration of the particle at the Acceleration of the particle at the disk sheet crossing is the main disk sheet crossing is the main source of the energetic ions.source of the energetic ions.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 1919
Thank you !!!Thank you !!!
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 2020
Spectra, integral moments, and Spectra, integral moments, and
composition (H, He, O, S) of composition (H, He, O, S) of
energetic ions (50 keV to 50 energetic ions (50 keV to 50 MeV) MeV)
are presented for selected Jupiter are presented for selected Jupiter
magnetospheric positions near magnetospheric positions near the the
equator between radial distances equator between radial distances of of
6 to 46 Jupiter radii (RJ), as 6 to 46 Jupiter radii (RJ), as
revealed by analysis of the revealed by analysis of the Galileo Galileo
Energetic Particle Detector data.Energetic Particle Detector data.
2MS3 , 14:20-14:40 October 13th, 2MS3 , 14:20-14:40 October 13th, 2011, SRI, Moscow2011, SRI, Moscow 2121
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