LESIA - Observatoire de Paris

Evolution of magnetic structures in the pre-phase of X class flares

mercredi 21 mars 2018, par Guiping Ruan (Shandong University, Weihai, Chine & LESIA)

Mercredi 28 mars 2018 à 11h00 , Lieu : Salle de conférence du bâtiment 17

We analysed the long term pre-flare conditions of X2.1 and X1.8 flares. The events respectively includes a sigmoidal filament eruption, a coronal mass ejection, and a GOES X flare from NOAA active region 11283. Based on the HMI observation, for an area along the polarity inversion line underneath the filament, we found gradual pre-eruption decreases of both the mean strength of the photospheric horizontal field (Bh) and the mean inclination angle. We propose that the pre-event evolution of Bh may be used to discern the driving mechanism of eruptions. We also showed the expansion of the arcades overlying the filament until the reconnection. The reconnection occurred between the arcades and the pre-existing magnetic field. A NLFFF modelling confirmed the present scenario. I will present the two projects that I started at the LESIA :
1. Study of eruptions and jets observed during a IRIS campaign with the MSDP of the solar tower.
2. Study of the prominence plasma characteristics based on IRIS Mg II line profiles and MSDP Halpha line and radiative codes developed in Czech Republic.

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