[en] Proton aurorae are a distinct class of auroral phenomena caused by energetic protons precipitating into a planetary atmosphere. The defining observational signature is atomic hydrogen emissions from the precipitating particles after they obtain an electron from the neutral atmospheric gas, a process known as charge exchange. Until now, proton aurorae have been observed at Earth only. Here, we present evidence of auroral activity driven by precipitating protons at Mars, using observations by the MAVEN spacecraft. We observed transient brightening of upper atmospheric hydrogen Lyman-α emission across the Martian dayside correlated with solar wind activity. The driving mechanism is one not found at Earth and originates from energetic neutral atom production by solar wind protons directly interacting with the extended hydrogen corona surrounding Mars. We characterize this new type of Martian aurora and compare the observed emissions with preliminary modelling guided by simultaneous in situ particle measurements. These observations provide insights into how the solar wind can directly deposit energy into the Martian atmosphere as well as all other planetary objects that are surrounded by a substantial neutral corona exposed to the solar wind.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Deighan, J. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Jain, S. K. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Chaffin, M. S. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Fang, X. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Halekas, J. S.; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
Clarke, J. T.; Center for Space Physics, Boston University, Boston, MA, USA
Schneider, N. M.; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Stewart, A. I. F.; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Chaufray, J.-Y.; LATMOS/IPSL, Guyancourt, France
Evans, J. S.; Computational Physics, Inc, Springfield, VA, USA
Stevens, M. H.; Space Science Division, Naval Research Laboratory, Washington, DC, USA
Mayyasi, M.; Center for Space Physics, Boston University, Boston, MA, USA
Stiepen, Arnaud ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Crismani, M. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
McClintock, W. E.; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Holsclaw, G. M. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
Lo, D. Y.; LPL, University of Arizona, Tucson, AZ, USA
Montmessin, F.; LATMOS/IPSL, Guyancourt, France
Lefèvre, F.; LATMOS/IPSL, Guyancourt, France
Jakosky, B. M. ; Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO, USA
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