Jupiter; Aurora; Hubble Space Telescope; main emission; Lisri
Abstract :
[en] The aurorae at Jupiter are made up of many different features associated with a variety of generation mechanisms. The main auroral emission, also known as the main oval, is the most prominent of them as it accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range. The energy of the precipitating electrons is a crucial parameter to characterize the processes at play which give rise to these auroral emissions, and the altitude of the emissions directly depends on this energy. Here we make use of far-UV (FUV) images acquired with the Advanced Camera for Surveys on board the Hubble Space Telescope and spectra acquired with the Space Telescope Imaging Spectrograph to measure the vertical profile of the main emissions. The altitude of the brightness peak as seen above the limb is ~ 400 km, which is significantly higher than the 250 km measured in the post-dusk sector by Galileo in the visible domain. However, a detailed analysis of the effect of hydrocarbon absorption, including both simulations and FUV spectral observations, indicates that FUV apparent vertical profiles should be considered with caution, as these observations are not incompatible with an emission peak located at 250 km. The analysis also calls for spectral observations to be carried out with an optimized geometry in order to remove observational ambiguities.
Research center :
LiSRI - Liège Space Research Institute - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Bonfond, Bertrand ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Gustin, Jacques ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Gérard, Jean-Claude ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Grodent, Denis ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Radioti, Aikaterini ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Palmaerts, Benjamin ; Université de Liège - ULiège > Form. doct. sc. (sc. spatiales - Bologne)
Badman, Sarah; Lancaster University
Khurana, Krishan; University of California, Los Angeles - UCLA
Tao, Chihiro; Institut de Recherche en Astrophysique et Planétologie
Language :
English
Title :
The far-ultraviolet main auroral emission at Jupiter – Part 2: Vertical emission profile
Boffi, F. R., Sirianni, M., Lucas, R. A., Walborn, N. R., and Proffitt, C. R.: Delivery of a new ACS SBC throughput curve for Synphot, Technical Instrument Report ACS 2008-002, STSCI, tIR ACS 2008-002, 2008.
Bonfond, B., Grodent, D., Gérard, J.-C., Radioti, A., Dols, V., Delamere, P. A., and Clarke, J. T.: The Io UV footprint: Location, inter-spot distances and tail vertical extent, J. Geophys. Res., 114, A07224, doi:10.1029/2009JA014312, 2009.
Bonfond, B., Grodent, D., Gérard, J.-C., Stallard, T., Clarke, J. T., Yoneda, M., Radioti, A., and Gustin, J.: Auroral evidence of Io's control over the magnetosphere of Jupiter, Geophys. Res. Lett., 39, L01105, doi:10.1029/2011GL050253, 2012.
Bonfond, B., Gustin, J., Gérard, J. C., Grodent, D., Radioti, A., Palmaerts, B., Badman, S. V., Khurana, K. K., and Tao, C.: The far-yltraviolet main auroral emission at Jupiter - Part 1: Dawn-dusk brightness asymmetries, Ann. Geophys., 33, 1203-1209, doi:10.5194/angeo-33-1203-2015, 2015.
Cohen, I. J. and Clarke, J. T.: Modeling of Jupiter's auroral curtain and upper atmospheric thermal structure, J. Geophys. Res.-Space, 116, A08205, doi:10.1029/2010JA016037, 2011.
Cravens, T. E.: Vibrationally excited molecular hydrogen in the upper atmosphere of Jupiter, J. Geophys. Res., 92, 11083-11100, doi:10.1029/JA092iA10p11083, 1987.
Delamere, P. A., Bagenal, F., Paranicas, C., Masters, A., Radioti, A., Bonfond, B., Ray, L., Jia, X., Nichols, J., and Arridge, C.: Solar Wind and Internally Driven Dynamics: Influences on Magnetodiscs and Auroral Responses, Space Sci. Rev., 187, 51-97, doi:10.1007/s11214-014-0075-1, 2014.
Gérard, J.-C., Bonfond, B., Gustin, J., Grodent, D., Clarke, J. T., Bisikalo, D., and Shematovich, V.: Altitude of Saturn's aurora and its implications for the characteristic energy of precipitated electrons, Geophys. Res. Lett., 36, L02202, doi:10.1029/2008GL036554, 2009.
Gérard, J.-C., Bonfond, B., Grodent, D., Radioti, A., Clarke, J. T., Gladstone, G. R., Waite, J. H., Bisikalo, D., and Shematovich, V. I.: Mapping the electron energy in Jupiter's aurora: Hubble spectral observations, J. Geophys. Res.-Space, 119, 9072-9088, doi:10.1002/2014JA020514, 2014.
Grodent, D.: A Brief Review of Ultraviolet Auroral Emissions on Giant Planets, Space Sci. Rev., 187, 23-50, doi:10.1007/s11214-014-0052-8, 2015.
Grodent, D., Waite, J., and Gérard, J.-C.: A self-consistent model of the Jovian auroral thermal structure, J. Geophys. Res., 106, 12933-12952, doi:10.1029/2000JA900129, 2001.
Grodent, D., Clarke, J. T., Kim, J., Waite, J. H., and Cowley, S. W. H.: Jupiter's main auroral oval observed with HST-STIS, J. Geophys. Res., 108, 1389, doi:10.1029/2003JA009921, 2003.
Grodent, D., Bonfond, B., Gérard, J.-C., Radioti, A., Gustin, J., Clarke, J. T., Nichols, J., and Connerney, J. E. P.: Auroral evidence of a localized magnetic anomaly in Jupiter's northern hemisphere, J. Geophys. Res., 113, A09201, doi:10.1029/2008JA013185, 2008.
Gustin, J., Gérard, J.-C., Grodent, D., Cowley, S. W. H., Clarke, J. T., and Grard, A.: Energy-flux relationship in the FUV Jovian aurora deduced from HST-STIS spectral observations, J. Geophys. Res., 109, A10205, doi:10.1029/2003JA010365, 2004.
Gustin, J., Cowley, S. W. H., Gérard, J.-C., Gladstone, G. R., Grodent, D., and Clarke, J. T.: Characteristics of Jovian morning bright FUV aurora from Hubble Space Telescope/Space Telescope Imaging Spectrograph imaging and spectral observations, J. Geophys. Res.-Space, 111, A09220, doi:10.1029/2006JA011730, 2006.
Hess, S., Bonfond, B., Chantry, V., Gérard, J.-C., Grodent, D., Jacobsen, S., and Radioti, A.: Evolution of the Io footprint brightness II: Modeling, Planet. Space Sci., 88, 76-85, doi:10.1016/j.pss.2013.08.005, 2013.
James, G. K., Ajello, J. M., and Pryor, W. R.: The middle ultraviolet-visible spectrum of H2 excited by electron impact, J. Geophys. Res., 103, 20113-20124, doi:10.1029/97JE03692, 1998.
Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, doi:10.1016/0032-0633(73)90093-7, 1973.
Lundin, R. and Sandahl, I.: Some characteristics of the parallel electric field acceleration of electrons over discrete auroral arcs as observed from two rocket flights, in: European Sounding Rocket, Balloon and Related Research, with Emphasis on Experiments at High Latitudes, edited by: Halvorsen, T. and Battrick, B., ESA Special Publication, 135, 125-136, 1978.
Nichols, J. D., Bunce, E. J., Clarke, J. T., Cowley, S. W. H., Gérard, J.-C., Grodent, D., and Pryor, W. R.: Response of Jupiter's UV auroras to interplanetary conditions as observed by the Hubble Space Telescope during the Cassini flyby campaign, J. Geophys. Res.-Space, 112, A02203, doi:10.1029/2006JA012005, 2007.
Nichols, J. D., Clarke, J. T., Gérard, J. C., Grodent, D., and Hansen, K. C.: Variation of different components of Jupiter's auroral emission, J. Geophys. Res.-Space, 114, A06210, doi:10.1029/2009JA014051, 2009.
Palmaerts, B., Radioti, A., Grodent, D., Chané, E., and Bonfond, B.: Transient small-scale structure in the main auroral emission at Jupiter, J. Geophys. Res. Space Physics, 119, 9931-9938, doi:10.1002/2014JA020688, 2015.
Radioti, A., Gérard, J.-C., Grodent, D., Bonfond, B., Krupp, N., and Woch, J.: Discontinuity in Jupiter's main auroral oval, J. Geophys. Res., 113, A01215, doi:10.1029/2007JA012610, 2008.
Ray, L. C., Ergun, R. E., Delamere, P. A., and Bagenal, F.: Magnetosphere-ionosphere coupling at Jupiter: A parameter space study, J. Geophys. Res.-Space, 117, A01205, doi:10.1029/2011JA016899, 2012.
Shematovich, V. I., Bisikalo, D. V., Gérard, J.-C., Cox, C., Bougher, S. W., and Leblanc, F.: Monte Carlo model of electron transport for the calculation of Mars dayglow emissions, J. Geophys. Res., 113, E02011, doi:10.1029/2007JE002938, 2008.
Uno, T., Kasaba, Y., Tao, C., Sakanoi, T., Kagitani, M., Fujisawa, S., Kita, H., and Badman, S. V.: Vertical emissivity profiles of Jupiter's northern H3+ and H2 infrared auroras observed by Subaru/IRCS, J. Geophys. Res.-Space, 119, 10219, doi:10.1002/2014JA020454, 2014.
Vasavada, A. R., Bouchez, A. H., Ingersoll, A. P., Little, B., Anger, C. D., and The Galileo SSI Team: Jupiter's visible aurora and Io footprint, J. Geophys. Res., 104, 27133-27142, 1999.
Vogt, M. F., Kivelson, M. G., Khurana, K. K., Walker, R. J., Bonfond, B., Grodent, D., and Radioti, A.: Improved mapping of Jupiter's auroral features to magnetospheric sources, J. Geophys. Res.-Space, 116, A03220, doi:10.1029/2010JA016148, 2011.
Yung, Y. L., Gladstone, G. R., Chang, K. M., Ajello, J. M., and Srivastava, S. K.: H2 fluorescence spectrum from 1200 to 1700 A by electron impact - Laboratory study and application to Jovian aurora, Astrophys. J., 254, L65-L69, doi:10.1086/183757, 1982.