Modes of radial plasma motion in planetary systems

An ISSI international team

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Modes of radial plasma motion in planetary systems

Chris Paranicas (1), Caitriona Jackman (2), Nick Sergis (3), Nick Achilleos (4), Maria Andriopoulou (5), Sarah Badman (6), George Hospodarsky (7), Xianzhe Jia (8), Krishan Khurana (9) , Norbert Krupp (10), Philippe Louarn (11), Elias Roussos (10), Michelle Thomsen (12), and Tim Kennelly (7)

Don G. Mitchell provided expertise to our team during telecons

Affiliations: (1) APL, (2) U of Southampton, (3) U of Athens, (4) U College London, (5) SRI/Graz, (6) U of Leicester, (7) U of Iowa, (8) U of Michigan, (9) UCLA, (10) MPS, (11) IRAP, (12) PSI

Team meetings and telecons:

Meeting in Athens, Greece during MOP, week of July 8, 2013

Meeting of entire team in Bern, Switzerland, week of October 21, 2013

Team telecon, February 17, 2014

Meeting in Goettingen, Germany during Cassini MAPS, week of June 16, 2014

Meeting of entire team in Bern, Switzerland, week of July 21, 2014

Team telecon, October 13, 2014

Publications resulting from this project:

Badman, S., et al. (2016), Weakening of Jupiter's aurorae in January, 2014, Geophys. Res. Lett., 43, 988-997

Hospodarsky, G. B., et al. (2015), Plasma wave observations with Cassini at Saturn, Yosemite Chapman Conference on M-I Coupling in the Solar System, under review

Jackman, C. M., et al. (2015), Field dipolarization in Saturn's magnetotail with planetward ion flows and energetic particle flow bursts: Evidence of quasi-steady reconnection, J. Geophys. Res., Space Physics, 120, doi:10.1002/2015JA020995.

Palmaerts, B., Roussos, E., N. Krupp, W. S. Kurth, D.G. Mitchell, and J. N. Yates (2016), Statistical analysis and multi-instrument overview of the quasi-periodic 1-hour pulsations in Saturn’s outer magnetosphere, Icarus, 271, 1-18.

Paranicas, C., et al. (2016), Effects of radial motion on interchange injections at Saturn, Icarus, 264, 342-351.

Roussos, E., et al. (2016), Quasi-periodic injections of relativistic electrons in Saturn’s outer magnetosphere, Icarus, 263, 101-116.

Thomsen, M. F., D. G. Mitchell, X. Jia, C. Jackman, G. Hospodarsky, and A. Coates (2015), Plasmapause formation at Saturn, J. Geophys. Res., Space Physics, 120, 2015JA021008.

Thomsen, M. F., D. B. Reisenfeld, R. J. Wilson, M. Andriopoulou, F. J. Crary, G. B. Hospodarsky, C. M. Jackman, X. Jia, K. K. Khurana, C. Paranicas, E. Roussos, N. Sergis, and R. L. Tokar (2014), Ion composition in interchange injection events in Saturn’s magnetosphere, J. Geophys. Res., 119, 9761-9772.

Themes from the work of the group:

Multi-instrument perspective on Saturnian injections

Consequences of finite radial speed on interchange injections

Quasi-periodic events

Reconnection and subsequent dynamics

Themes from the original proposal:

Heavy reliance on Cassini observations. The relevant spacecraft data show many examples of transport events including clear signatures in the magnetometer, the cold plasma, the energetic charged and neutral particle, and the wave data. For example, transport events have been detected in the wave data, usually appearing as changes in the upper-hybrid emission (decrease in density), enhanced electron cyclotron harmonic [ECH] emissions, and/or enhanced whistler mode emission. The Cassini/RPWS instrument is especially sensitive to young (minutes-old) injection events (Kennelly et al. 2013), allowing the distribution of these young events to be determined before magnetospheric processes have a chance to disrupt their spatial organization. On the other hand, energetic charged particle data are very good for studying older injection events (e.g., Paranicas et al. 2010). Cassini ENA imaging can track injected distributions from the tail region to deep within the magnetosphere. Finally the footprint of both small- and large-scale injections are seen as intense arcs or patches in the aurora (e.g., Mauk et al. 2002; Bunce et al. 2005). By characterising the different auroral emissions (their morphology, intensity, location, temporal evolution) as signatures of injection events by comparison with the other in situ and remote measurements, we will be able to use future auroral observations as an invaluable diagnostic of the mode of plasma transport in the magnetosphere even without in situ spacecraft measurements (Badman et al. 2013).

A great deal is known about azimuthal motion in the Jovian and Saturnian systems, but less is understood about how plasma and energetic charged particles move radially.

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