ORCID Profile
0000-0003-3990-670X
Current Organisation
Northumbria University
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Publisher: American Geophysical Union (AGU)
Date: 12-2012
DOI: 10.1029/2012JA018201
Publisher: Elsevier BV
Date: 11-2007
Publisher: Elsevier BV
Date: 11-2002
Publisher: American Geophysical Union (AGU)
Date: 04-2012
DOI: 10.1029/2012GL051312
Publisher: Springer Science and Business Media LLC
Date: 11-2008
DOI: 10.1038/NATURE07440
Abstract: The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H(3)(+) infrared emission. Although the morphology of these aurorae is affected by changes in the solar wind, the source of the currents which produce them is a matter of debate. Recent models predict only weak emission away from the main auroral oval. Here we report images that show emission both poleward and equatorward of the main oval (separated by a region of low emission). The extensive polar emission is highly variable with time, and disappears when the main oval has a spiral morphology this suggests that although the polar emission may be associated with minor increases in the dynamic pressure from the solar wind, it is not directly linked to strong magnetospheric compressions. This aurora appears to be unique to Saturn and cannot be explained using our current understanding of Saturn's magnetosphere. The equatorward arc of emission exists only on the nightside of the planet, and arises from internal magnetospheric processes that are currently unknown.
Publisher: Springer Science and Business Media LLC
Date: 06-2008
DOI: 10.1038/NATURE07077
Abstract: Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.
Publisher: American Geophysical Union (AGU)
Date: 2012
DOI: 10.1029/2011JA017222
Publisher: Springer Science and Business Media LLC
Date: 10-09-2011
Publisher: American Geophysical Union (AGU)
Date: 04-2017
DOI: 10.1002/2017JA023918
Publisher: Springer Science and Business Media LLC
Date: 05-1999
DOI: 10.1038/20121
Publisher: Elsevier BV
Date: 07-2007
Publisher: Elsevier BV
Date: 12-2014
Publisher: American Geophysical Union (AGU)
Date: 02-2011
DOI: 10.1029/2010GL046193
Publisher: American Astronomical Society
Date: 08-01-2008
DOI: 10.1086/527545
Publisher: Elsevier BV
Date: 2005
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Tom Stallard.