the role of the magnetodisk in the jupiter's magnetosphere

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


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.



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)


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.



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


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.


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.


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.


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



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


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


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


““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


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.


Thank you !!!Thank you !!!


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.


the role of the magnetodisk in the jupiter's magnetosphere

Documents

dipole field

field lines

module magnetic field

measured field strength

magnetic eld

moscow black streamlines

jupiter magnetosphere

radial distance r