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Auroral hiss, electron beams and standing Alfvén wave currents near Saturn's moon Enceladus
Schippers, P.; Gurnett, D. A.; Persoon, A. M. +8 more
Observations from the Cassini spacecraft have shown that Saturn's small icy moon Enceladus ejects a plume of water vapor and small ice particles into Saturn's rapidly co-rotating magnetosphere. In this paper we show that the interaction of the moon with the magnetospheric plasma produces a number of electrodynamics effects that are remarkably simi…
The search for Titan lightning radio emissions
Gurnett, D. A.; Fischer, G.
We report on the non-detection of radio emissions indicative of Titan lightning by the Cassini RPWS (Radio and Plasma Wave Science) instrument. A previous study by Fischer et al. (2007) investigated the first 35 Titan flybys, and here we continue our search until the end of Cassini's equinox mission. No bursts that would clearly indicate the exist…
Saturn's equatorial oscillation: Evidence of descending thermal structure from Cassini radio occultations
French, R. G.; Flasar, F. M.; Rappaport, N. J. +7 more
A series of near-equatorial radio occultations of Cassini by Saturn occurred in 2005 and again in 2009-2010. Comparison of the temperature-pressure profiles obtained from the two sets of occultations shows evidence of a descending pattern in the stratosphere that is similar to those associated with equatorial oscillations in Earth's middle atmosph…
Supercorotating return flow from reconnection in Saturn's magnetotail
Coates, A. J.; Dougherty, M. K.; Thomsen, M. F. +4 more
Detecting plasma dynamics in Saturn's magnetosphere is essential for understanding energy flow through the system. It has been proposed that both the Dungey and Vasyliunas cycles operate at Saturn, and the competition between these cycles has been debated. We examine data taken by the Cassini spacecraft in Saturn's post-dawn magnetosphere, ∼17.5 S…
The global energy balance of Titan
West, Robert A.; Baines, Kevin H.; Nixon, Conor A. +12 more
The global energy budget of planets and their moons is a critical factor to influence the climate change on these objects. Here we report the first measurement of the global emitted power of Titan. Long-term (2004-2010) observations conducted by the Composite Infrared Spectrometer (CIRS) onboard Cassini reveal that the total emitted power by Titan…
Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region
Retinò, Alessandro; Khotyaintsev, Yuri; Vaivads, Andris +3 more
We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at ∼-10 RE. We find that the interaction between the earthward moving fast plasma jet and the high-β ambient plasma in the plasma sheet results in magnetic pileup and compression ahea…
On accelerated magnetosheath flows under northward IMF
Farrugia, C. J.; Erkaev, N. V.; Harris, B. +1 more
We study the acceleration of magnetosheath plasma using a semi-analytical magnetic string approach for a range of solar wind Alfvén Mach numbers, MA, between 2 and 20. We work with an IMF vector perpendicular to the solar wind velocity, Vsw, and pointing north. We do not invoke magnetic reconnection. Our results indicate that…
Mode conversion between Alfvén and slow waves observed in the magnetotail by THEMIS
Zhang, T. L.; Glassmeier, K. -H.; Nakamura, R. +6 more
We present the direct spacecraft observations of wave mode conversion in the magnetotail for the first time. On February 28, 2008, the satellites P4 and P3 of THEMIS observe wave signals with a period of about 100 s in the magnetotail at about 11 RE. At the same time, geomagnetic activity is very quiet and there are no wave signals obse…
Simulating the time-dependent response of Titan's upper atmosphere to periods of magnetospheric forcing
Westlake, Joseph; Waite, J. Hunter, Jr.; Bell, Jared M.
We demonstrate that a simulation of Titan's upper atmosphere can exhibit significant short-term temperature variations when exposed to globally averaged plasma heating rates over periods of 8 Earth days (0.5 Titan days). Temperature enhancements can range from 16 K when exposed to column-integrated, orbit-averaged heating rates of 2.5 × 108
Long term time variations of the suprathermal ions in Saturn's magnetosphere
Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C. +1 more
We use the Charge-Energy-Mass Spectrometer (CHEMS) on Cassini to study long-term time variations of the suprathermal (E/Q = 27-220 keV/e) ions in Saturn's equatorial ring current (Latitude = -10° to 10°, dipole L = 7-16) from the end of 2004 to the end of 2010. We identify five equatorial time periods, which vary in length from 124 to 282 days, an…