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Pulsations of the polar cusp aurora at Saturn
Author(s) -
Palmaerts B.,
Radioti A.,
Roussos E.,
Grodent D.,
Gérard J.C.,
Krupp N.,
Mitchell D. G.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023497
Subject(s) - physics , ionosphere , saturn , interplanetary magnetic field , magnetopause , magnetosphere , solar wind , polar , magnetic reconnection , noon , astrophysics , magnetosphere of saturn , geophysics , astronomy , cusp (singularity) , atmospheric sciences , planet , magnetic field , geometry , mathematics , quantum mechanics
The magnetospheric cusp is a region connecting the interplanetary environment to the ionosphere and enabling solar wind particles to reach the ionosphere. We report the detection of several isolated high‐latitude auroral emissions with the Ultraviolet Imaging Spectrograph of the Cassini spacecraft. We suggest that these auroral spots, located in the dawn‐to‐noon sector and poleward of the main emission, are the ionospheric signatures of the magnetospheric cusp, in agreement with some previous observations with the Hubble Space Telescope. The high‐latitude cusp auroral signature has been associated with high‐latitude lobe reconnection in the presence of a southward interplanetary magnetic field. The occurrence rate of the polar cusp aurora suggests that lobe reconnection is frequent at Saturn. Several auroral imaging sequences reveal a quasiperiodic brightening of the polar cusp aurora with a period in the range of 60 to 70 min. Similar pulsations in the energetic electron fluxes and in the azimuthal component of the magnetic field are simultaneously observed by Cassini instruments, suggesting the presence of field‐aligned currents. Pulsed dayside magnetopause reconnection is a likely common triggering process for the cusp auroral brightenings at Saturn and the quasiperiodic pulsations in the high‐latitude energetic electron fluxes.