Reference : Conversion from HST ACS and STIS auroral counts into brightness, precipitated power, ...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/128466
Conversion from HST ACS and STIS auroral counts into brightness, precipitated power, and radiated power for H2 giant planets
English
Gustin, Jacques mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Physique des atmosphères et des environnements planétaires >]
Bonfond, Bertrand mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Grodent, Denis mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Physique des atmosphères et des environnements planétaires >]
Gérard, Jean-Claude mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO) >]
1-Jul-2012
Journal of Geophysical Research. Space Physics
American Geophysical Union (AGU)
117
07316
Yes (verified by ORBi)
International
0148-0227
Washington
DC
[en] Atmospheric Composition and Structure: Airglow and aurora ; Atmospheric Composition and Structure: Planetary atmospheres (5210 ; 5405 ; 5704) ; Atmospheric Composition and Structure: Thermosphere: energy deposition (3369) ; Atmospheric Composition and Structure: Instruments and techniques ; Magnetospheric Physics: Auroral phenomena (2407)
[en] The STIS and ACS instruments onboard HST are widely used to study the giant planet's aurora. Several assumptions have to be made to convert the instrumental counts into meaningful physical values (type and bandwidth of the filters, definition of the physical units, etc…), but these may significantly differ from one author to another, which makes it difficult to compare the auroral characteristics published in different studies. We present a method to convert the counts obtained in representative ACS and STIS imaging modes/filters used by the auroral scientific community to brightness, precipitated power and radiated power in the ultraviolet (700-1800 Å). Since hydrocarbon absorption may considerably affect the observed auroral emission, the conversion factors are determined for several attenuation levels. Several properties of the auroral emission have been determined: the fraction of the H[SUB]2[/SUB] emission shortward and longward of the HLy-α line is 50.3% and 49.7% respectively, the contribution of HLy-α to the total unabsorbed auroral signal has been set to 9.1% and an input of 1 mW m[SUP]-2[/SUP] produces 10 kR of H[SUB]2[/SUB] in the Lyman and Werner bands. A first application sets the order of magnitude of Saturn's auroral characteristics in the total UV bandwidth to a brightness of 10 kR and an emitted power of ˜2.8 GW. A second application uses published brightnesses of Europa's footprint to determine the current density associated with the Europa auroral spot: 0.21 and 0.045 μA m[SUP]-2[/SUP] assuming no hydrocarbon absorption and a color ratio of 2, respectively. Factors to extend the brightnesses observed with Cassini-UVIS to total H[SUB]2[/SUB] UV brightnesses are also provided.
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/128466
10.1029/2012JA017607
http://adsabs.harvard.edu/abs/2012JGRA..11707316G

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