| Autor: |
Allegrini, F.1,2 fallegrini@swri.edu, Kurth, W. S.3, Elliott, S. S.3, Saur, J.4, Livadiotis, G.1, Nicolaou, G.1, Bagenal, F.5, Bolton, S.1, Clark, G.6, Connerney, J. E. P.7,8, Ebert, R. W.1,2, Gladstone, G. R.1,2, Louarn, P.9, Mauk, B. H.6, McComas, D. J.10, Sulaiman, A. H.3, Szalay, J. R.10, Valek, P. W.1, Wilson, R. J.5 |
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| Zdroj: |
Journal of Geophysical Research. Space Physics. Sep2021, Vol. 126 Issue 9, p1-16. 16p. |
| Abstrakt: |
We present a survey of electron partial densities (i.e., the portion of the total density measured between ∼0.05 and 100 keV) and temperatures in Jupiter's main auroral emission region using plasma measurements from the Jovian Auroral Distributions Experiment (JADE) on Juno. The electron partial density increases from ∼0.01 or 0.1 cm−3 near the main oval to a few cm−3 at the edge of the measurable part of the UV emission equatorward of the main oval. The electron temperature is highest near the main oval at ∼10–20 keV and decreases equatorward down to ∼0.3–2 keV. The JADE electron partial density agrees within a factor of ∼2 with the total electron densities derived from Juno‐Waves when the comparison is possible. The electron density and temperature trends are consistent for all sampled longitudes, for the north and the south, and there is no significant trend with radial distance in the range examined in this study (1.25–1.96 RJ). The electron density is anti‐correlated with the temperature and the characteristic energy. The ratio of the magnetic field strength to the electron density is maximum near the main oval. Plain Language Summary: The very intense ultraviolet (UV) aurora at Jupiter is caused by energetic electrons precipitating from the magnetosphere into the atmosphere where they excite molecular hydrogen. The Jovian Auroral Distributions Experiment (JADE) on Juno measures electron pitch angle and energy distributions from ∼50 eV to ∼100 keV. Investigating the characteristics of electron distributions at these energies is critical for understanding the source population for the electrons that produce Jupiter's UV aurora and the mechanisms that accelerate them to keV and MeV energies. In this study, we present a survey of electron densities and temperatures derived from JADE in Jupiter's polar magnetosphere. The electron density from JADE agrees very well with that obtained from Juno's Waves instrument, using a different and independent method. We find that the electron densities over the main emissions increase with decreasing latitudes and the electron temperatures increase with increasing latitudes. These trends are independent of longitude, hemisphere, or altitude. The electron density and temperature are anti‐correlated. The ratio of the magnetic field strength to the electron density is maximum near the main oval where accelerated electron distributions are observed. Key Points: We present a survey of auroral electrons properties (partial density and temperature) over Jupiter's main auroral regionThe electron density (temperature) increases (decreases) equatorward of the main oval, and density and temperature are anti‐correlatedThe ratio of B/n follows the same trend as the electron characteristic energy and is maximum near the main oval [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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