The University of Southampton
University of Southampton Institutional Repository

Magnetic reconnection and associated transient phenomena within the magnetospheres of Jupiter and Saturn

Magnetic reconnection and associated transient phenomena within the magnetospheres of Jupiter and Saturn
Magnetic reconnection and associated transient phenomena within the magnetospheres of Jupiter and Saturn

We review in situ observations made in Jupiter and Saturn’s magnetosphere that illustrate the possible roles of magnetic reconnection in rapidly-rotating magnetospheres. In the Earth’s solar wind-driven magnetosphere, the magnetospheric convection is classically described as a cycle of dayside opening and tail closing reconnection (the Dungey cycle). For the rapidly-rotating Jovian and Kronian magnetospheres, heavily populated by internal plasma sources, the classical concept (the Vasyliunas cycle) is that the magnetic reconnection plays a key role in the final stage of the radial plasma transport across the disk. By cutting and closing flux tubes that have been elongated by the rotational stress, the reconnection process would lead to the formation of plasmoids that propagate down the tail, contributing to the final evacuation of the internally produced plasma and allowing the return of the magnetic flux toward the planet. This process has been studied by inspecting possible ‘local’ signatures of the reconnection, as magnetic field reversals, plasma flow anisotropies, energetic particle bursts, and more global consequences on the magnetospheric activity.

The investigations made at Jupiter support the concept of an ‘average’ X-line, extended in the dawn/dusk direction and located at 90–120 Jovian radius (RJ) on the night side. The existence of a similar average X-line has not yet been established at Saturn, perhaps by lack of statistics. Both at Jupiter and Saturn, the reconfiguration signatures are consistent with magnetospheric dipolarizations and formation of plasmoids and flux ropes. In several cases, the reconfigurations also appear to be closely associated with large scale activations of the magnetosphere, seen from the radio and auroral emissions. Nevertheless, the statistical study also suggests that the reconnection events and the associated plasmoids are not frequent enough to explain a plasma evacuation that matches the mass input rate from the satellites and the rings. Different forms of transport should thus act together to evacuate the plasma, which still needs to be established. Investigations of reconnection signatures at the magnetopause and other processes as the Kelvin-Helmholtz instability are also reviewed. A provisional conclusion would be that the dayside reconnection is unlikely a crucial process in the overall dynamics. On the small scales, the detailed analysis of one reconnection event at Jupiter shows that the local plasma signatures (field-aligned flows, energetic particle bursts…) are very similar to those observed at Earth, with likely a similar scaling with respect to characteristic kinetic lengths (Larmor radius and inertial scales).

Giant planet, Magnetosphere
0038-6308
181-227
Louarn, Philippe
0315d27b-ca57-439a-92f2-981fda036887
Andre, Nicolas
210d2676-9716-4567-bc3a-2f4dfdb34f9b
Jackman, Caitriona M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Kasahara, Satoshi
c91ccc9f-69f1-4275-b20f-80bc73be3680
Kronberg, Elena A.
1de51184-0fa8-4fb9-9c83-60fb9e21be2c
Vogt, Marissa F.
7a00094d-e760-44eb-bf65-4135d218932b
Louarn, Philippe
0315d27b-ca57-439a-92f2-981fda036887
Andre, Nicolas
210d2676-9716-4567-bc3a-2f4dfdb34f9b
Jackman, Caitriona M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Kasahara, Satoshi
c91ccc9f-69f1-4275-b20f-80bc73be3680
Kronberg, Elena A.
1de51184-0fa8-4fb9-9c83-60fb9e21be2c
Vogt, Marissa F.
7a00094d-e760-44eb-bf65-4135d218932b

Louarn, Philippe, Andre, Nicolas, Jackman, Caitriona M., Kasahara, Satoshi, Kronberg, Elena A. and Vogt, Marissa F. (2015) Magnetic reconnection and associated transient phenomena within the magnetospheres of Jupiter and Saturn. Space Science Reviews, 187 (1-4), 181-227. (doi:10.1007/s11214-014-0047-5).

Record type: Review

Abstract

We review in situ observations made in Jupiter and Saturn’s magnetosphere that illustrate the possible roles of magnetic reconnection in rapidly-rotating magnetospheres. In the Earth’s solar wind-driven magnetosphere, the magnetospheric convection is classically described as a cycle of dayside opening and tail closing reconnection (the Dungey cycle). For the rapidly-rotating Jovian and Kronian magnetospheres, heavily populated by internal plasma sources, the classical concept (the Vasyliunas cycle) is that the magnetic reconnection plays a key role in the final stage of the radial plasma transport across the disk. By cutting and closing flux tubes that have been elongated by the rotational stress, the reconnection process would lead to the formation of plasmoids that propagate down the tail, contributing to the final evacuation of the internally produced plasma and allowing the return of the magnetic flux toward the planet. This process has been studied by inspecting possible ‘local’ signatures of the reconnection, as magnetic field reversals, plasma flow anisotropies, energetic particle bursts, and more global consequences on the magnetospheric activity.

The investigations made at Jupiter support the concept of an ‘average’ X-line, extended in the dawn/dusk direction and located at 90–120 Jovian radius (RJ) on the night side. The existence of a similar average X-line has not yet been established at Saturn, perhaps by lack of statistics. Both at Jupiter and Saturn, the reconfiguration signatures are consistent with magnetospheric dipolarizations and formation of plasmoids and flux ropes. In several cases, the reconfigurations also appear to be closely associated with large scale activations of the magnetosphere, seen from the radio and auroral emissions. Nevertheless, the statistical study also suggests that the reconnection events and the associated plasmoids are not frequent enough to explain a plasma evacuation that matches the mass input rate from the satellites and the rings. Different forms of transport should thus act together to evacuate the plasma, which still needs to be established. Investigations of reconnection signatures at the magnetopause and other processes as the Kelvin-Helmholtz instability are also reviewed. A provisional conclusion would be that the dayside reconnection is unlikely a crucial process in the overall dynamics. On the small scales, the detailed analysis of one reconnection event at Jupiter shows that the local plasma signatures (field-aligned flows, energetic particle bursts…) are very similar to those observed at Earth, with likely a similar scaling with respect to characteristic kinetic lengths (Larmor radius and inertial scales).

Full text not available from this repository.

More information

e-pub ahead of print date: 15 May 2015
Keywords: Giant planet, Magnetosphere

Identifiers

Local EPrints ID: 436460
URI: http://eprints.soton.ac.uk/id/eprint/436460
ISSN: 0038-6308
PURE UUID: 342cf5c2-c2f1-4a0f-83bb-da7847eaded9
ORCID for Caitriona M. Jackman: ORCID iD orcid.org/0000-0003-0635-7361

Catalogue record

Date deposited: 11 Dec 2019 17:30
Last modified: 07 Oct 2020 02:04

Export record

Altmetrics

Contributors

Author: Philippe Louarn
Author: Nicolas Andre
Author: Caitriona M. Jackman ORCID iD
Author: Satoshi Kasahara
Author: Elena A. Kronberg
Author: Marissa F. Vogt

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×