Séminaire de Carl Schmidt (Boston University), le Mardi 26 septembre à 11h à Jussieu + Zoom

Annonce transmise par Benoît Lavraud (LAB)

Bonjour,

Carl Schmidt, professeur à Boston University, donnera un séminaire le Mardi 26/09 à 11h, dans la salle des séminaires du couloir du 2ème étage, entre les tours 46 et 56 à Jussieu.

Titre du séminaire: Io's Atmosphere, Ionosphere, and Plasma Torus

Résumé: The Io plasma torus offers our only opportunity to take a picture of a planetary magnetosphere. Torus ion emissions are excited through electron impact and so line ratios of like ion species can effectively map the plasma density and electron temperature. This provides us with some empirical constraints on the upstream plasma conditions that sweep past the moon. A rich spectrum of emission features is seen local to Io because of its interaction with the torus, and dozens of transitions in Io's atmosphere and ionosphere are not observable anywhere else. Photochemical and plasma-induced emission channels can be disentangled by comparing telescope spectra in sunlight to eclipsed spectra in Jupiter's shadow. The vapor pressure equilibrium of Io's bulk SO2 atmosphere is tipped out of balance during Io's ingress and egress. Comparing the temporal response of SO2 to Io's atomic emissions reveals important new clues on the atomic production pathways. Plasma induced atomic lines are a confluence of several processes including direct excitation of the atoms, dissociative excitation of molecules, recombination reactions in Io's ionosphere, and, in the case of forbidden transitions, collisional quenching. Sunlight and electron impacts can also ionize, and any ions created in collisionless regions are ripped out of Io's atmosphere by Jupiter's magnetic field. This ion population not only re-supplies the torus, causing feedback, it can also dissociatively recombine or charge exchange to form streams of energetic neutral atoms. Doppler shift can distinguish such neutrals borne of ionic parents. With velocities well above the jovian escape speed, these energetic neutral atoms can paint the surfaces of the other satellites or populate Jupiter's diffuse and dynamic nebulae, one of the largest structures in our solar system with a volume exceeding the Sun itself.

Un lien Zoom est disponible pour suivre le séminaire à distance:
https://cnrs.zoom.us/j/94357278706?pwd=d2dQT2FMWmY1cmxHYjNBMlZqSjAxQT09
ID de réunion : 943 5727 8706
Code secret : 07vsmg

N'hésitez pas à faire circuler l'annonce aux collègues qui pourraient être intéressés.

Cordialement,
Dimitra Koutroumpa