Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Complex structure within Saturn’s infrared aurora
AU - Stallard, Tom
AU - Miller, Steve
AU - Lystrup, Makenzie
AU - Achilleos, Nicholas
AU - Bunce, Emma
AU - Arridge, Christopher
AU - Dougherty, Michele
AU - Cowley, Stan
AU - Badman, Sarah V.
AU - Talboys, Dean
AU - Brown, Robert
AU - Baines, Kevin
AU - Buratti, Bonnie
AU - Clark, Roger
AU - Sotin, Christophe
AU - Nicholson, Phil
AU - Drossart, Pierre
PY - 2008/11
Y1 - 2008/11
N2 - 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 H3+ 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.
AB - 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 H3+ 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.
UR - http://www.scopus.com/inward/record.url?scp=56249102776&partnerID=8YFLogxK
U2 - 10.1038/nature07440
DO - 10.1038/nature07440
M3 - Journal article
AN - SCOPUS:56249102776
VL - 456
SP - 214
EP - 217
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7219
ER -