The sub‐Alfvénic interaction of the Galilean satellites with the Jovian magnetosphere

Neubauer, F. M.

doi:10.1029/97je03370

Cited by 233 publications

(383 citation statements)

References 47 publications

Supporting

Mentioning

364

Contrasting

Unclassified

Order By: Relevance

“…Unfortunately, Callisto's orbit lies at such distances that the magnetic field through the moon maps to higher magnetic latitudes, within an almost omnipresent main aurora Neubauer [ 1998;1999] has discussed the expected Alfvtn wings associated with Callisto and his results are consistent with the observations. The purpose of this paper is to report the discovery of statistically significant control of a portion of the DAM radio emission by Callisto.…”

Section: Introductionsupporting

confidence: 80%

Control of Jovian radio emission by Callisto

Menietti

Gurnett

Christopher

2001

Geophysical Research Letters

View full text Add to dashboard Cite

Abstract. Galileo has been in orbit around Jupiter since December 1995 and a large database has been collected. We present the results of a survey of the plasma wave data for the frequency range 2.0 MHz to 5.6 MHz, the low frequency decametric (DAM) emissions. While the control of a portion of the radio emission by the moon Io is well known, and Ganymede control has been more recently indicated, we report that a small but significant portion of DAM emission is seen to be correlated with the orbital phase of Callisto. While the occurrence rate of emission controlled by Ganymede and Callisto is considerably less than for Io, the power levels can be nearly the same. We estimate the power of the Callisto-dependent emission to be ~70% of the Io-dependent radio emission and about the same as the Ganymede-dependent radio emission. This result indicates an Alfvtn current system associated with Callisto, and thus a significant interaction of the magnetosphere of Callisto with that of Jupiter as is believed to exist for both Io and Ganymede.

show abstract

Section: Introductionsupporting

confidence: 80%

Control of Jovian radio emission by Callisto

Menietti

Gurnett

Christopher

2001

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…These currents would produce a secondary (or induced) magnetic field that adds to the background field of Jupiter and to fields arising from currents flowing in the ambient plasma to give the total observed field. Khurana et al (1998) and Kivelson et al (1999) recently showed that the dominant large-scale features of magnetic field perturbations observed by the Galileo spacecraft during flybys of both Europa and Callisto are consistent with induced magnetic dipoles, as had also been pointed out by Neubauer (1998). At both moons, the observed magnetic field perturbations are approximately those expected for moons responding as perfectly conducting spheres.…”

Section: Introductionsupporting

confidence: 55%

Subsurface Oceans on Europa and Callisto: Constraints from Galileo Magnetometer Observations

Zimmer

Khurana

Kivelson

2000

Icarus

331

361

View full text Add to dashboard Cite

Magnetic field perturbations measured during Galileo flybys of Europa and Callisto are consistent with dipole fields induced by the temporal variations of the ambient jovian magnetospheric field. These fields are close to those expected for perfectly conducting moons. We investigate the implications of these observations for the electrical structure of the moon's interiors using a simple shell model. It is found that Europa and Callisto must possess regions where the conductivity exceeds 0.06 and 0.02 S/m at a depth of less than 200 and 300 km below the surface, respectively. This conductivity is unattainable in ice or silicates, unless the ice layer is at least partially molten or very large temperature gradients can be maintained below the ice. An ionosphere or a cloud of pick-up ions are probably also insufficiently conductive. Global Earth-like oceans under the surface of both moons could account for the observations provided they are at least a few kilometers thick.

show abstract

“…In neither of these extreme cases does coupling to the ionosphere damp the waves. [Neubauer, 1998], the rate of such pickup in a low-density neutral cloud is too low to yield the values required for the fixedend boundary conditions.…”

Section: Implications For the Electrical Conductivity Of Ganymede Or mentioning

confidence: 99%

“…There is clear evidence that on those passes Galileo encountered field lines linked to Ganymede at most at one end, with the other end linked to Jupiter's ionosphere [Williams et al, 1997a;1998]. The final pass (designated G8, as it occurred on Galileo's eighth orbit around Jupiter) cut through the upstream magnetosphere with closest approach at 28.3 ø Ganymede latitude at an altitude of 1606 km or 0.61 RG, with Ganymede's radius RG = 2634 km.…”

mentioning

confidence: 99%

“…The final pass (designated G8, as it occurred on Galileo's eighth orbit around Jupiter) cut through the upstream magnetosphere with closest approach at 28.3 ø Ganymede latitude at an altitude of 1606 km or 0.61 RG, with Ganymede's radius RG = 2634 km. We believe that on this pass Galileo entered a region of closed magnetic field lines, that is, magnetic field lines connected to the moon on both ends [Williams et al, 1997b, 1998]. Here we will argue that oscillations in the magnetic field observed near closest approach can be interpreted as field line resonances ].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Probing Ganymede's magnetosphere with field line resonances

Volwerk¹,

Kivelson²,

Khurana³

et al. 1999

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. We report on the spectrum of field line resonances identified in data acquired by the Galileo spacecraft within Ganymede' s magnetosphere on a relatively low latitude pass. We infer properties of the plasma distribution and its transport from the observed spectrum. The harmonic structure in the spectrum of the magnetometer data agrees very well with the freq_3uencies predicted for resonances of a dipole field. The spectrum implies a density of 2 amu cm near the equator on closed field lines of Ganymede's magnetic field inside of 2 RG (Ganymede radii). This density is significantly r3educed relative to the local density of the Jovian plasma sheet near Ganymede (_< 8 electrons cm-, or -100 amu cm -3 for an average ion mass per charge of 20 amu and average charge of 1.5 electron charges). A shadowing effect of Ganymede for the flow of particles injected at a reconnection layer on the side of the moon downstream relative to the direction of torus plasma flow accounts for the marked density depletion.Implications for conducting paths near Ganymede's surface are considered.

show abstract

The sub‐Alfvénic interaction of the Galilean satellites with the Jovian magnetosphere

Cited by 233 publications

References 47 publications

Control of Jovian radio emission by Callisto

Control of Jovian radio emission by Callisto

Subsurface Oceans on Europa and Callisto: Constraints from Galileo Magnetometer Observations

Probing Ganymede's magnetosphere with field line resonances

Contact Info

Product

Resources

About