LESIA - Observatoire de Paris

Jupiter/Saturn H3+ Auroral Emission Model for Electron Energy Estimation

Thursday 28 February 2013, by Chihiro Tao (Laboratoire de Physique des Plasmas (LPP), Ecole Polytechnique)

Thursday 28 March 2013 à 11h00 , Lieu : Salle de conférence du bât. 17

Auroral electron energy is a key parameter as reflecting the magnetospheric activities and controlling upper atmospheric heating and conductance. We investigate the feasibility of characterizing the Jovian auroral electron energy and flux via H3+ infrared (IR) emission line analysis instead of traditional method via ultraviolet (UV) emission. Ground based telescopes can monitor Jovian infrared auroral activities continuously for an extended time interval compared to the more restricted temporal coverage of ultraviolet observations. Since the departure from local thermodynamic equilibrium (LTE) varies with vibrational levels and altitude, measurements of the relative emission line intensities reveal the altitude of emission and hence the electron energy. The combination of three H3+ line-intensity ratios is required to determine the electron energy and the background temperature. The feasibility issue is evaluated by studying how the observational error propagates into the error of the estimated electron energy. We also test this method to multi-line analysis and much better accuracy is expected. Since saturnian H3+ emissions vary far more substantially according to temperature variations, the method described here is not applicable to observations of Saturn. In this seminar, I would like to discuss several predictions for the magnetosphere-ionosphere coupling system from our model.


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