Observatoire de Paris Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Origins of density fluctuations
 in the solar corona explored with time-dependent MHD simulations

lundi 17 juin 2019, par Léa Griton (IRAP)

Mardi 18 juin 2019 à 11h00 , Lieu : Salle de conférence du bâtiment 16

Quasi-periodic density fluctuations appear ubiquitous in the regions where the solar wind forms and accelerates. The origin of these fluctuations is still debated and could result from a number of physical processes including rising MHD waves, periodic impulsive heating or continual magnetic reconnection. The recent analysis of deep field imaging campaigns carried out with the STEREO COR-2 instrument highlight the omnipresence of density fluctuations with periodicities around 40 minutes in both fast and slow solar winds. We use the time-dependent model of the solar wind MULTI-VP already tested against observations for a steady-state corona, to explore the mechanisms at play in the low corona that could produce such density fluctuations higher up in the atmosphere. We first test the idea that impulsive and periodic heating near the transition region could lead to density fluctuations higher up in the atmosphere. We investigate how such density fluctuations can be transmitted out in the solar wind beyond the sonic point. This study provides a modeling framework for the future analysis that can be carry out with the remote-sensing and in situ data that will be acquired by the Parker Solar Probe and the Solar Orbiter over the next decade.

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