[en] Recently, a transient localized brightness enhancement has been observed in Jupiter's main auroral emission close to noon by Palmaerts et al. (2014). We use results from three-dimensional global MHD simulations to understand what is causing this localized peak in the main emission. In the simulations, the peak occurs every rotation period and is due to shearing motions in the magnetodisk. These shearing motions are caused by heavy flux-tubes being accelerated to large azimuthal speeds at dawn. The centrifugal force acting on these flux-tubes is then so high that they rapidly move away from the planet. When they reach noon, their azimuthal velocity decreases, thus reducing the centrifugal force, and allowing the flux-tubes to move back closer to Jupiter. The shearing motions associated with this periodic phenomenon locally increase the field aligned currents in the simulations, thus causing a transient brightness enhancement in the main auroral emission, similar to the one observed by Palmaerts et al. (2014).
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Chané, Emmanuel; Centre for mathematical Plasma Astrophysics, KU Leuven, Leuven, Belgium
Palmaerts, Benjamin ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Radioti, Aikaterini ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Language :
English
Title :
Periodic shearing motions in the Jovian magnetosphere causing a localized peak in the main auroral emission close to noon
Badman, S.V., Branduardi-Raymont, G., Galand, M., Hess, S.L.G., Krupp, N., Lamy, L., Melin, H., Tao, C., Auroral processes at the giant planets: energy deposition, emission mechanisms, morphology and spectra. Space Sci. Rev. 187 (Apr. 2015), 99–179.
Bunce, E.J., Cowley, S.W.H., Divergence of the equatorial current in the dawn sector of Jupiter's magnetosphere: analysis of Pioneer and Voyager magnetic field data. Planet. Space Sci. 49 (Aug. 2001), 1089–1113.
Chané E., Saur, J., Keppens, R., Poedts, S., How is the Jovian main auroral emission affected by the solar wind?. J. Geophys. Res. Space Phys. 122 (Feb. 2017), 1960–1978.
Chané E., Saur, J., Poedts, S., Modeling Jupiter's magnetosphere: Influence of the internal sources. J. Geophys. Res. Space Phys. 118 (May 2013), 2157–2172.
Clarke,.T., Grodent, D., Cowley, S.W.H., Bunce, E.J., Zarka, P., Connerney,.E.P., Satoh, T., Jupiter's aurora. Bagenal, F., Dowling, T.E., McKinnon, W.B., (eds.) Jupiter. The Planet, Satellites and Magnetosphere, 2004, 639–670.
Cowley, S.W.H., Bunce, E.J., Origin of the main auroral oval in Jupiter's coupled magnetosphere-ionosphere system. Planet. Space Sci. 49 (Aug. 2001), 1067–1088.
Frank, L., Paterson, W., Plasmas observed near local noon in Jupiter's magnetosphere with the galileo spacecraft. J. Geophys. Res. Space Phys., 109(A11), 2004.
Grodent, D., A brief review of ultraviolet auroral emissions on giant planets. Space Sci. Rev. 187 (Apr. 2015), 23–50.
Hill, T.W., The Jovian auroral oval. J. Geophys. Res. 106 (May 2001), 8101–8108.
Keppens, R., Meliani, Z., van Marle, A.J., Delmont, P., Vlasis, A., van der Holst, B., Parallel, grid-adaptive approaches for relativistic hydro and magnetohydrodynamics. Comput. Phys. 231 (Feb. 2012), 718–744.
Krupp, N., Vasyliunas, V.M., Woch,., Lagg, A., Khurana, K.K., Kivelson, M.G., Mauk, B.H., Roelof, E.C., Williams, D.J., Krimigis, S.M., Kurth, W.S., Frank, L.A., Paterson, W.R., Dynamics of the Jovian magnetosphere. Bagenal, F., Dowling, T.E., McKinnon, W.B., (eds.) upiter. The Planet, Satellites and Magnetosphere, 2004, 617–638.
Moriguchi, T., Nakamizo, A., Tanaka, T., Obara, T., Shimazu, H., Current systems in the Jovian magnetosphere. J. Geophys. Res. Space Phys., 113, May 2008 A05204.
Nichols,.D., Yeoman, T.K., Bunce, E.J., Chowdhury, M.N., Cowley, S.W.H., Robinson, T.R., Periodic emission within Jupiter's main auroral oval. J. Geophys. Res. Lett., 2017 https://doi.org/10.1002/2017GL074824.
Palmaerts, B., Radioti, A., Grodent, D., Chané E., Bonfond, B., Transient small-scale structure in the main auroral emission at Jupiter. J. Geophys. Res. Space Phys. 119:12 (2014), 9931–9938.
Porth, O., Xia, C., Hendrix, T., Moschou, S.P., Keppens, R., MPI-AMRVAC for solar and astrophysics. ApJS, 214, Sep. 2014, 4.
Radioti, A., Gérard, J.-C., Grodent, D., Bonfond, B., Krupp, N., Woch, Discontinuity in Jupiter's main auroral oval. J. Geophys. Res. Space Phys., 113, an. 2008 A01215.
Radioti, A., Grodent, D., Gérard, J..-C., Southwood, D.J., Chané E., Bonfond, B., Pryor, W., Stagnation of saturn's auroral emission at noon. J. Geophys. Res. Space Phys. 122:6 (2017), 6078–6087 2016JA023820.
Southwood, D.J., Chané E., High-latitude circulation in giant planet magnetospheres. J. Geophys. Res. Space Phys. 121:6 (2016), 5394–5403 2015JA022310.
Waldrop, L., Roelof, E., Fritz, T., Three-dimensional convective flows of energetic ions in Jupiter's equatorial magnetosphere. J. Geophys. Res. Space Phys., 120(12), 2015.
Woch,., Krupp, N., Lagg, A., Tomás, A., The structure and dynamics of theJovian energetic particle distribution. Adv. Space Res. 33 (an. 2004), 2030–2038.
Xia, C., Teunissen,., El Mellah, I., Chané E., Keppens, R., Mpi-amrvac 2.0 for solar and astrophysical applications. Astrophys. J. Suppl. Ser., 234(2), 2018, 30.
