What is the role of magnetic null points in large flares?

Brigitte Schmieder (1, 2) , Cristina H. Mandrini (3) , Pascal Démoulin (1, 2) , Guillaume Aulanier (1, 2) , Hui Li (4) , Arkadiusz Berlicki (5)

1 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
2 Physique solaire
3 IAFE - Instituto de Astronomía y Física del Espacio, Universidade de Buenos Aires
4 Purple Mountain Observatory
5 Astronomical Institute, University of Wroclaw

We have performed the analysis of the magnetic topology of active region NOAA 10486 before two large flares occurring on October 26 and 28, 2003. The 3D extrapolation of the photospheric magnetic field shows the existence of magnetic null points when using two different methods. We use TRACE 1600 Å and 195 Å brightenings as tracers of the energy release due to magnetic reconnections. We conclude on the three following points: The small events observed before the flares are related to low lying null points. They are long lasting and associated with low energy release. They are not triggering the large flares.

Domaines: Astrophysique [astro-ph]

Brigitte Schmieder, Cristina H. Mandrini, Pascal Démoulin, Guillaume Aulanier, Hui Li, et al.. What is the role of magnetic null points in large flares?. Advances in Space Research, 2007, 39, pp.1840-1846. ⟨10.1016/j.asr.2007.03.058⟩. ⟨hal-03786171⟩