Universität zu Köln

Szalay, J. R., Bonfond, B., Allegrini, F., Bagenal, F., Bolton, S., Clark, G., Connerney, J. E. P., Ebert, R. W., Ergun, R. E., Gladstone, G. R., Grodent, D., Hospodarsky, G. B., Hue, V., Kurth, W. S., Kotsiaros, S., Levin, S. M., Louarn, P., Mauk, B., McComas, D. J., Saur, J., Valek, P. W. and Wilson, R. J. (2018). In Situ Observations Connected to the Io Footprint Tail Aurora. J. Geophys. Res.-Planets, 123 (11). S. 3061 - 3078. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9100

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Abstract

The Juno spacecraft crossed flux tubes connected to the Io footprint tail at low Jovian altitudes on multiple occasions. The transits covered longitudinal separations of approximately 10 degrees to 120 degrees along the footprint tail. Juno's suite of magnetospheric instruments acquired detailed measurements of the Io footprint tail. Juno observed planetward electron energy fluxes of similar to 70mW/m(2) near the Io footprint and similar to 10mW/m(2) farther down the tail, along with correlated, intense electric and magnetic wave signatures, which also decreased down the tail. All observed electron distributions were broad in energy, suggesting a dominantly broadband acceleration process, and did not show any broad inverted-V structure that would be indicative of acceleration by a quasi-static, discrete, parallel potential. Observed waves were primarily below the proton cyclotron frequency, yet identification of a definitive wave mode is elusive. Beyond 40 degrees down the footprint tail, Juno observed depleted upward loss cones, suggesting that the broadband acceleration occurred at distances beyond Juno's transit distance of 1.3 to 1.7R(J). For all transits, Juno observed fine structure on scales of approximately tens of kilometers and confirmed independently with electron and wave measurements that a bifurcated tail can intermittently exist. Plain Language Summary The Juno spacecraft crossed regions magnetically connected to auroral structures associated with Jupiter's moon Io on multiple occasions. The transits covered longitudinal separations of approximately 10 degrees to 120 degrees along Io's auroral tail. Juno's suite of instruments acquired detailed measurements of these auroral structures. Juno directly observed the electrons that sustain these auroral features before they crash into the atmosphere and generate the brilliant aurora. The flux of these electrons decreased as Juno transited the tail farther from Io's longitude. While there are two main explanations for Io's auroral signatures, the nature of the observed electrons in this work favors one mechanism over the other. When Juno was far from Io's longitude, the observations suggest that the spacecraft was below the point at which the electrons are accelerated into the atmosphere. For all transits, Juno observed fine structure on scales of approximately tens of kilometers and confirmed that a bifurcated tail can intermittently exist.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Szalay, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bonfond, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Allegrini, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bagenal, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bolton, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Clark, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Connerney, J. E. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ebert, R. W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ergun, R. E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gladstone, G. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grodent, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hospodarsky, G. B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hue, V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kurth, W. S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kotsiaros, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Levin, S. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Louarn, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mauk, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED McComas, D. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Saur, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Valek, P. W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wilson, R. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-168432
DOI:	10.1029/2018JE005752
Journal or Publication Title:	J. Geophys. Res.-Planets
Volume:	123
Number:	11
Page Range:	S. 3061 - 3078
Date:	2018
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WAVE CURRENT SYSTEM; ELECTRON-BEAMS; FLUX TUBE; JUPITER; MAGNETOSPHERE; ACCELERATION; ENVIRONMENT; GENERATION; WAKE Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16843