Saturn's magnetic field revealed by the Cassini Grand Finale
journal contribution
posted on 2019-03-20, 09:25 authored by MK Dougherty, H Cao, KK Khurana, GJ Hunt, G Provan, S Kellock, ME Burton, TA Burk, EJ Bunce, SWH Cowley, MG Kivelson, CT Russell, DJ SouthwoodDuring 2017, the Cassini fluxgate magnetometer made in situ measurements of Saturn's magnetic field at distances ~2550 ± 1290 kilometers above the 1-bar surface during 22 highly inclined Grand Finale orbits. These observations refine the extreme axisymmetry of Saturn's internal magnetic field and show displacement of the magnetic equator northward from the planet's physical equator. Persistent small-scale magnetic structures, corresponding to high-degree (>3) axisymmetric magnetic moments, were observed. This suggests secondary shallow dynamo action in the semiconducting region of Saturn's interior. Some high-degree magnetic moments could arise from strong high-latitude concentrations of magnetic flux within the planet's deep dynamo. A strong field-aligned current (FAC) system is located between Saturn and the inner edge of its D-ring, with strength comparable to the high-latitude auroral FACs. [See also erratum]
Funding
H.C. acknowledges Royal Society Grant RP\EA\180014 to enable an academic visit to Imperial College London, during which some of the work has been carried out. Work at Imperial College London was funded by Science and Technology Facilities Council (STFC) consolidated grant ST/N000692/1. M.K.D. is funded by Royal Society Research Professorship RP140004. H.C. is funded by NASA’s CDAPS program NNX15AL11G and NASA Jet Propulsion Laboratory (JPL) contract 1579625. Work at the University of Leicester was supported by STFC grant ST/N000749/1. E.J.B. is supported by a Royal Society Wolfson Research Merit Award. Work at the University of California, Los Angeles is funded by NASA JPL contract 1409809. K.K.K. is funded by NASA JPL contract 1409806:033. M.G.K. is funded by JPL under contract 1416974 at the University of Michigan. M.E.B. and T.A.B. are supported by the Cassini Project.
History
Citation
Science, 2018, 362 (6410)Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and AstronomyVersion
- AM (Accepted Manuscript)
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SciencePublisher
American Association for the Advancement of Scienceeissn
1095-9203Acceptance date
2018-09-05Copyright date
2018Available date
2019-03-20Publisher DOI
Publisher version
http://science.sciencemag.org/content/362/6410/eaat5434Notes
Erratum for the Research Article “Saturn’s magnetic field revealed by the Cassini Grand Finale” by M. K. Dougherty, H. Cao, K. K. Khurana, G. J. Hunt, G. Provan, S. Kellock, M. E. Burton, T. A. Burk, E. J. Bunce, S. W. H. Cowley, M. G. Kivelson, C. T. Russell, D. J. Southwood Science 12 Oct 2018: Vol. 362, Issue 6411, eaav6732 DOI: 10.1126/science.aav6732 In the Research Article “Saturn’s magnetic field revealed by the Cassini Grand Finale,” a copyediting error led to the inadvertent omission of the sign of the value for Gauss coefficient g70 in Table 1 online. The correct value is –59.6. The online version has been corrected. In addition, the authors corrected three supplementary figure callouts on p. 6 and an in-text citation on p. 7.Language
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