Detecting a solar energetic particle event with Solar Orbiter

The Energetic Particle Detector (EPD) instrument on ESA’s Solar Orbiter measures the composition, timing and other properties of energetic particles from solar eruptions and solar flares. The plots show the increased flux of energetic particles detected by the instrument on 19 June 2020, a few days after Solar Orbiter passed perihelion, the point in its orbit closest to the Sun.These particles were coming from the sunward hemisphere and in both plots, the x axis represents time and the y axis shows the particle’s energy. The top panel is from the EPD Electron Proton Telescope (EPD/EPT) detector, and the bottom panel is from EPD SupraThermal Electron and  Proton (EPD/STEP) detector.

“The Sun is very quiet now and the occurrence of solar energetic particle (SEP) events is very seldom but this is the first event detected by EPD so far, so for us is really special,” says Javier Rodriguez-Pacheco, Principal Investigator of EPD.

Once in the scientific phase of the mission, it is expected that the solar energetic activity will increase and the frequency of SEP events will be higher. Comparison of the in situ instrument data with observations from the remote sensing instruments will allow a better understanding of the source and acceleration mechanisms of the Solar Energetic Particles.

Solar Orbiter is a space mission of international collaboration between ESA and NASA.