An isolated, bright cusp aurora at Saturn
File(s)
Author(s)
Type
Journal Article
Abstract
Saturn's dayside aurora displays a number of morphological features poleward of the main emission region. We present an unusual morphology captured by the Hubble Space Telescope on 14 June 2014 (day 165), where for 2 h, Saturn's FUV aurora faded almost entirely, with the exception of a distinct emission spot at high latitude. The spot remained fixed in local time between 10 and 15 LT and moved poleward to a minimum colatitude of ~4°. It was bright and persistent, displaying intensities of up to 49 kR over a lifetime of 2 h. Interestingly, the spot constituted the entirety of the northern auroral emission, with no emissions present at any other local time—including Saturn's characteristic dawn arc, the complete absence of which is rarely observed. Solar wind parameters from propagation models, together with a Cassini magnetopause crossing and solar wind encounter, indicate that Saturn's magnetosphere was likely to have been embedded in a rarefaction region, resulting in an expanded magnetosphere configuration during the interval. We infer that the spot was sustained by reconnection either poleward of the cusp or at low latitudes under a strong component of interplanetary magnetic field transverse to the solar wind flow. The subsequent poleward motion could then arise from either reconfiguration of successive open field lines across the polar cap or convection of newly opened field lines. We also consider the possible modulation of the feature by planetary period rotating current systems.
Date Issued
2017-06-13
Date Acceptance
2017-05-23
Citation
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2017, 122 (6), pp.6121-6138
ISSN
2169-9380
Publisher
American Geophysical Union
Start Page
6121
End Page
6138
Journal / Book Title
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
Volume
122
Issue
6
Copyright Statement
©2017. The Authors.
This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000405534800017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
Saturn
aurora
cusp
reconnection
magnetosphere
INTERPLANETARY MAGNETIC-FIELD
HUBBLE-SPACE-TELESCOPE
PLANETARY PERIOD OSCILLATIONS
WIND DYNAMIC PRESSURE
ALIGNED CURRENTS
POLAR CUSP
MAGNETOSPHERE
RECONNECTION
MAGNETOPAUSE
MAGNETOTAIL
Publication Status
Published