[en] Trihydrogen cations (H3+), a key diagnostic of atmospheric energy balance, are produced through ionization by solar radiation and particle impacts in hydrogen-rich planetary atmospheres. At Jupiter, H3+ is produced most efficiently in the auroral region through
electron precipitation and plays a leading role in magnetosphere-ionosphere coupling by
regulating ionospheric conductance. Previously, the properties of H3+ have been determined
from remote sensing, with plasma parameters retrieved from its infrared emissions, although
these measurements are limited by line-of-sight integration and restricted altitude resolution. Here, we report the unambiguous, direct in-situ detection of H3+ plasma in the auroral region. Unexpectedly, intermittent H3+ outflows are measured high above the ionosphere, with upward velocities exceeding Jupiter’s escape speed, confirming atmospheric escape of H3+. We propose that H3+ outflow originates in the auroral upward electric current region, initially triggered by plasma-wave interactions and subsequently accelerated by the electric potential structure above the ionosphere. This study reveals a new H3+-mediated pathway for mass and energy transfer between the ionosphere and magnetosphere of Jupiter, constituting an important contribution to atmospheric escape with a loss rate of order 1026/s. Similar mechanisms may operate at other planets with infrared aurorae and strong magnetic fields.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Wang, Jian-Zhao; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, USA
Bagenal, Fran; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, USA
Szalay, Jamey; Department of Astrophysical Sciences, Princeton University, Princeton, USA
Valek, Philip; Southwest Research Institute, USA
Sulaiman, Ali; School of Physics and Astronomy, University of Minnesota, Minneapolis, USA
Ray, Licia; Physics Department, Lancaster University, Lancaster, UK
Bonfond, Bertrand ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Wilson, Robert; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, USA
Ebert, Robert; Southwest Research Institute, USA ; Department of Physics and Astronomy, University of Texas at San Antonio, USA
Allegrini, Frederic; Southwest Research Institute, USA ; Department of Physics and Astronomy, University of Texas at San Antonio, USA
Clark, George; Applied Physics Laboratory, The Johns Hopkins University, Laurel, USA
Kim, Thomas; Space Science and Applications Group, Los Alamos National Laboratory, Los Alamos, USA
Language :
English
Title :
Ionospheric Escape of H 3 + from Jupiter's Polar Regions
