Anti-planetward auroral electron beams at Saturn

Area of Science:

• Space Physics
• Plasma Physics
• Planetary Science

Background:

• Discrete auroras are typically caused by electrons accelerated towards a planet.
• Recent observations have revealed electrons accelerating away from planets, a phenomenon with uncertain mechanisms and significance.
• The role of upward electron acceleration in auroral processes has been unclear, with limited observational data.

Purpose of the Study:

• To investigate the phenomenon of anti-planetward electron acceleration in Saturn's magnetosphere.
• To determine if this upward acceleration is a universal feature of auroral processes across different planets.
• To assess the significance of upward electron acceleration in the overall auroral energy budget.

Main Methods:

• Analysis of electron beam acceleration in Saturn's magnetosphere.
• Comparison of energy spectra and fluxes of electron beams with those observed at Earth and Jupiter.
• Statistical mapping of magnetic field lines to identify regions of aurora associated with upward electron acceleration.

Main Results:

• Observed anti-planetward acceleration of electron beams in Saturn's magnetosphere.
• Electron beam energy spectra at Saturn are qualitatively similar to those at Earth.
• Energy fluxes in Saturn's upward electron beams are comparable to energies required for auroral excitation.

Conclusions:

• Anti-planetward electron acceleration is a universal feature of auroral processes, observed at Earth, Jupiter, and Saturn.
• Upward electron acceleration is an essential component of the auroral process, not merely a special case.
• These findings necessitate a revised understanding of magnetospheric physics and auroral generation mechanisms.