odonoghue_et_al_2017.pdf (1.16 MB)
Redetection of the Ionospheric H-3(+) Signature of Saturn's "Ring Rain"
journal contributionposted on 2018-06-04, 14:34 authored by James O'Donoghue, Luke Moore, John E. P. Connerney, Henrik Melin, Tom S. Stallard, SSteve Miller, Kevin H. Baines
In April 2011 Saturn’s midlatitude ionospheric H+ 3 emissions were detected, exhibiting anomalous (nonsolar) H+ 3 latitudinal variations consistent with the transport of water from specific locations in Saturn’s rings, known as “ring rain”. These products, transported to the planet along the magnetic field, may help to explain the unusual pattern of peaks and troughs in electron densities discovered in Saturn’s ionosphere by spacecraft flybys. In the present study, we analyzed H+ 3 emissions recorded on 23 April 2013, showing for the first time since the original detection that Saturn’s midlatitude H+ 3 emissions are indeed heavily modified. Although the 2013 emissions are dimmer by almost a factor of 3.7, the latitudinal contrast is greater and uncertainties are lower. Increased H+ 3 intensities were found near planetocentric latitudes of 43∘, 51∘, and 63∘, previously identified with sources at the inner edge of the B ring, A ring, and the orbit of Enceladus and associated E ring.
James O’Donoghue’s research was supported by an appointment to the National Aeronautics and Space Administration (NASA) Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASA. This material is based upon work supported by NASA under grants NNX14AG72G and NNX17AF14G issued through the SSO Planetary Astronomy Program. Henrik Melin and Tom Stallard were supported by the Science and Technology Facilities Council under grant ST/K001000/1. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and the data in the form of fits files are available from the Keck archive at https://www2.keck.hawaii.edu/koa/ public/koa.php. We are grateful to the staff at the Keck Observatory. The authors wish to recognize the significant cultural role and reverence that the summit of Mauna Kea has within the indigenous Hawaiian community: we are fortunate to have the opportunity to conduct observations from this mountain.
CitationGeophysical Research Letters, 2017, 44 (23), pp. 11762-11769 (8)
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
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