Alexis Rouillard (CNRS, IRAP, Toulouse, France)

Probing the origin of solar energetic particles using combined remote sensing and in-situ measurements
When Oct 14, 2014 from 11:00 AM to 12:00 PM
What
  • Special Seminar
  • Colloquium
Where SH, Seminar Room
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The origin of the most energetic solar particles released during solar storms is still debated. In this study, combined observations and modelling techniques are used to test the hypothesis that the most energetic solar energetic particles (SEPs) are accelerated by coronal shock waves. Combined STEREO SOHO and SDO observations allow us to reconstruct the 3-D extent of pressure waves formed during the eruption of coronal mass ejections. We concentrate on the proton-rich events detected by the near-Earth spacecraft and the STEREOs between 2011 to 2014. The SEPs measured in situ during these episodes of propagating coronal waves propagate along coronal and interplanetary magnetic field lines between the Sun and 1 AU. We use a combination of observations and modelling to reconstruct the 3-D location of magnetic field lines and thereby establish the magnetic connectivity between the shock near the Sun and the points of in-situ measurements near 1AU. This 3-D localisation allows us to determine the (1) the height and spatial extent of the pressure waves at the SEP release times near the Sun, (2) compare the longitudinal extent of SEP events with the extent of the pressure waves. We combine a 1D Solar Wind hydrodynamical code (VP code) with a potential model of the solar corona to compute the density, bulk speed, ion and electron temperatures and pressures along the relevant magnetic flux tubes. This allows us to compute the characteristic speeds of the medium and the fast and slow-mode speeds at the potential shock transition. We compare the properties of the inferred shocks with those of the SEPs measured in situ.