Solar energetic particles

This visualization of particle acceleration across a shock is a simplified representation of shock drift acceleration showing the motion of electrons (yellow) and protons (blue).
Animation of NASA's STEREO coronagraph during a coronal mass ejection followed by solar energetic particles

Solar energetic particles (SEP), formerly known as solar cosmic rays, are high-energy, charged particles originating in the solar atmosphere and solar wind. They consist of protons, electrons and heavy ions with energies ranging from a few tens of keV to many GeV. The exact processes involved in transferring energy to SEPs is a subject of ongoing study.

SEPs are relevant to the field of space weather, as they are responsible for SEP events and ground level enhancements.