posted on 2018-06-04, 14:34authored byJames 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.
Funding
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.
History
Citation
Geophysical Research Letters, 2017, 44 (23), pp. 11762-11769 (8)
Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy