Variation of Saturn's UV aurora with SKR phase

Jonathan D. Nichols (1) , Baptiste Cecconi (2, 3) , John T. Clarke (4) , S. W. H. Cowley (1) , Jean-Claude Gérard (5) , A. Grocott (1) , D. C. Grodent (5) , Laurent Lamy (6, 2, 3) , Philippe Zarka (2, 3)

1 Department of Physics and Astronomy, University of Leicester
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 Physique des plasmas
4 Center for Space Physics, Boston University
5 LPAP - Laboratoire de Physique Atmosphérique et Planétaire
6 Imperial College London

It is well known that a wide range of kronian magnetospheric phenomena, including the Saturn kilometric radiation (SKR), exhibit oscillations near the planetary rotation period. However, although the SKR is believed to be generated by unstable auroral electrons, no connection has been established to date between diurnal SKR modulations and UV auroral power. We use an empirical SKR phase determined from Cassini observations to order the `quiet time' total emitted UV auroral power as observed by the Hubble Space Telescope in programs during the interval 2005-2009. Our results indicate that both the northern and southern UV powers are dependent on SKR phase, varying diurnally by factors of ˜3. We also show that the UV variation originates principally from the morning half of the oval, consistent with previous observations of the SKR sources.

Domaines: Astrophysique [astro-ph]; Planète et Univers [physics]

Jonathan D. Nichols, Baptiste Cecconi, John T. Clarke, S. W. H. Cowley, Jean-Claude Gérard, et al.. Variation of Saturn's UV aurora with SKR phase. Geophysical Research Letters, 2010, 37 (L15102), pp.15102. ⟨10.1029/2010GL044057⟩. ⟨hal-03796874⟩