Saturn's magnetic field revealed by the Cassini Grand Finale

Michele K Dougherty; Hao Cao; Krishan K Khurana; Gregory J Hunt; Gabrielle Provan; Stephen Kellock; Marcia E Burton; Thomas A Burk; Emma J Bunce; Stanley W H Cowley; Margaret G Kivelson; Christopher T Russell; David J Southwood

doi:10.1126/science.aat5434

Saturn's magnetic field revealed by the Cassini Grand Finale

Science. 2018 Oct 5;362(6410):eaat5434. doi: 10.1126/science.aat5434.

Authors

Michele K Dougherty¹, Hao Cao^{2

3}, Krishan K Khurana⁴, Gregory J Hunt⁵, Gabrielle Provan⁶, Stephen Kellock⁵, Marcia E Burton⁷, Thomas A Burk⁷, Emma J Bunce⁶, Stanley W H Cowley⁶, Margaret G Kivelson^{4

8}, Christopher T Russell⁴, David J Southwood⁵

Affiliations

¹ Physics Department, The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK. m.dougherty@imperial.ac.uk.
² Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA.
³ Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125, USA.
⁴ Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90025, USA.
⁵ Physics Department, The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK.
⁶ Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK.
⁷ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
⁸ Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 40109, USA.

PMID: 30287636
DOI: 10.1126/science.aat5434

Abstract

During 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.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't