Universität zu Köln

Szalay, J. R., Allegrini, F., Bagenal, F., Bolton, S. J., Bonfond, B., Clark, G., Connerney, J. E. P., Ebert, R. W., Gershman, D. J., Giles, R. S., Gladstone, G. R., Greathouse, T., Hospodarsky, G. B., Imai, M., Kurth, W. S., Kotsiaros, S., Louarn, P., McComas, D. J., Saur, J., Sulaiman, A. H. and Wilson, R. J. (2020). Alfvenic Acceleration Sustains Ganymede's Footprint Tail Aurora. Geophys. Res. Lett., 47 (3). WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 1944-8007

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Abstract

Integrating simultaneous in situ measurements of magnetic field fluctuations, precipitating electrons, and ultraviolet auroral emissions, we find that Alfvenic acceleration mechanisms are responsible for Ganymede's auroral footprint tail. Magnetic field perturbations exhibit enhanced Alfvenic activity with Poynting fluxes of similar to 100 mW/m(2). These perturbations are capable of accelerating the observed broadband electrons with precipitating fluxes of similar to 11 mW/m(2), such that Alfvenic power is transferred to electron acceleration with similar to 10% efficiency. The ultraviolet emissions are consistent with in situ electron measurements, indicating 13 +/- 3 mW/m(2) of precipitating electron flux. Juno crosses flux tubes with both upward and downward currents connected to the auroral tail exhibiting small-scale structure. We identify an upward electron conic in the downward current region, possibly due to acceleration by inertial Alfven waves near the Jovian ionosphere. In concert with in situ observations at Io's footprint tail, these results suggest that Alfvenic acceleration processes are broadly applicable to magnetosphere-satellite interactions. Plain Language Summary Jupiter's moon Ganymede interacts with the planet's rapidly rotating magnetic field, which generates an aurora in the Jovian upper atmosphere. The Juno spacecraft crossed magnetic field lines connected to this aurora. We found that a specific type of wave, similar to a wave produced when a string is plucked, is responsible for accelerating the electrons sustaining this aurora. This type of interaction between a moon and the planet it orbits is likely a common process occurring at other exoplanetary systems.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Szalay, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Allegrini, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bagenal, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bolton, S. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bonfond, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Clark, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Connerney, J. E. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ebert, R. W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gershman, D. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Giles, R. S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gladstone, G. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Greathouse, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hospodarsky, G. B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Imai, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kurth, W. S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kotsiaros, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Louarn, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED McComas, D. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Saur, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sulaiman, A. H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wilson, R. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-344733
DOI:	10.1029/2019GL086527
Journal or Publication Title:	Geophys. Res. Lett.
Volume:	47
Number:	3
Date:	2020
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	1944-8007
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ELECTRON ACCELERATION; JUNO OBSERVATIONS; IO; MODEL; FIELD; EMISSIONS; CONICS; REGION Multiple languages Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/34473