Details

Autor(en) / Beteiligte

• Allegrini, F.
• Mauk, B.
• Clark, G.
• Gladstone, G. R.
• Hue, V.
• Kurth, W. S.
• Bagenal, F.
• Bolton, S.
• Bonfond, B.
• Connerney, J. E. P.
• Ebert, R. W.
• Greathouse, T.
• Imai, M.
• Levin, S.
• Louarn, P.
• McComas, D. J.
• Saur, J.
• Szalay, J. R.
• Valek, P. W.
• Wilson, R. J.

Titel

Energy Flux and Characteristic Energy of Electrons Over Jupiter's Main Auroral Emission

Ist Teil von

• Journal of geophysical research. Space physics, 2020-04, Vol.125 (4), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• Jupiter's ultraviolet (UV) aurorae, the most powerful and intense in the solar system, are caused by energetic electrons precipitating from the magnetosphere into the atmosphere where they excite the molecular hydrogen. Previous studies focused on case analyses and/or greater than 30‐keV energy electrons. Here for the first time we provide a comprehensive evaluation of Jovian auroral electron characteristics over the entire relevant range of energies (~100 eV to ~1 MeV). The focus is on the first eight perijoves providing a coarse but complete System III view of the northern and southern auroral regions with corresponding UV observations. The latest magnetic field model JRM09 with a current sheet model is used to map Juno's magnetic foot point onto the UV images and relate the electron measurements to the UV features. We find a recurring pattern where the 3‐ to 30‐keV electron energy flux peaks in a region just equatorward of the main emission. The region corresponds to a minimum of the electron characteristic energy (<10 keV). Its polarward edge corresponds to the equatorward edge of the main oval, which is mapped at M shells of ~51. A refined current sheet model will likely bring this boundary closer to the expected 20–30 RJ. Outside that region, the >100‐keV electrons contribute to most (>~70–80%) of the total downward energy flux and the characteristic energy is usually around 100 keV or higher. We examine the UV brightness per incident energy flux as a function of characteristic energy and compare it to expectations from a model. Plain Language Summary Aurorae, also commonly called Northern or Southern Lights, are among the most spectacular displays of nature. They are observed not only at Earth but at other planets too, such as Mars, Jupiter, and Saturn. In fact, Jupiter has the brightest aurora in the solar system. The aurora is created when electrons and/or ions in space precipitate into the atmosphere and excite the ambient gas. At Jupiter, they mostly shine in the ultraviolet which is invisible to our eyes but can be seen with suitable instrumentation. The faster the electrons, the deeper they go into the atmosphere, but also the more energy they carry, which eventually can be converted to create more light. This study is about characterizing the electrons that create Jupiter's aurora using many instruments from the National Aeronautics and Space Administration's Juno Mission. We find that different ultraviolet emissions correspond to different electron characteristics. Knowing the differences will help us to understand the bigger picture to explain the processes that create the aurora. Key Points We present a survey of Jovian auroral electrons characteristics from 50 eV to 1000 keV by Juno We present a metric to identify main oval crossings in electron data using 3‐30 keV electrons energy flux We estimate the UV brightness per incident electron energy flux as a function of characteristic energy