• DOI:10.1038/S41550-018-0538-5
• Corpus ID: 105560692

Discovery of a proton aurora at Mars

@article{Deighan2018DiscoveryOA,
  title={Discovery of a proton aurora at Mars},
  author={Justin I. Deighan and S. K. Jain and Michael Scott Chaffin and Xiaoliang Fang and Jasper S. Halekas and John T. Clarke and N. Schneider and A. Ian F. Stewart and J-Y. Chaufray and J. Scott Evans and Michael H. Stevens and Majd Mayyasi and Arnaud Stiepen and Matteo Crismani and William E. McClintock and Gregory M. Holsclaw and Daniel Y. Lo and Franck Montmessin and Franck Lef{\'e}vre and Bruce M. Jakosky},
  journal={Nature Astronomy},
  year={2018},
  volume={2},
  pages={802-807}
}

• J. Deighan, S. Jain, +17 authors B. Jakosky
• Published 1 December 2016
• Physics
• Nature Astronomy

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.The MAVEN spacecraft observed brightening in the Lyman-α line correlated with solar wind activity, which can be attributed to auroral activity by solar wind protons interacting with the Martian neutral hydrogen corona. Proton aurorae are normally seen at Earth only.