Fredagskollokvium: Magnetohydrodynamics simulations of eruptive phenomena in the solar atmosphere

Dr. Avijeet Prasad, Rosseland Centre for Solar Physics (RoCS), UiO.

smiling young men with glasses
Avijeet Prasad, postdoctoral fellow at Rosseland Centre for Solar Physics (RoCS), UiO.

Solar eruptive phenomena, like flares and coronal mass ejections (CMEs), are explosive events occurring in the solar atmosphere that involve the rapid release of huge quantities of energy. The electromagnetic radiation, energetic particles and magnetic field produced by flares and carried by CMEs can affect interplanetary space weather and Earth's geomagnetic field, leading to effects like disruption of satellite navigation systems and failure of power grids at high latitudes. This makes an understanding of the eruptive phenomena quite indispensable.

In this talk I will present a magnetohydrodynamics simulation study of active region NOAA 11283 initialised using a non-force-free magnetic field extrapolated from a photospheric vector magnetogram. In particular, I would focus on the magnetic reconnections at a magnetic null point that resulted in the X2.1 flare on 2011 September 6 around 22:21 UT  followed by the appearance of circular flare ribbons and coronal dimmings (transient regions of reduced coronal emission in extreme-ultraviolet).

plot showing flare ribbons on the solar atmosphere
Comparison of the magnetic field topology with flare ribbons observed in SDO/AIA 304 A and a ring-shaped dimming region calculated from SDO/AIA 211 A, showing an excellent agreement with the field lines constituting the dome of the 3D null, the circular flare ribbons, and the ring-shaped dimming region. Credits: Prasad et al. 2020

 

Emneord: institute seminar, solfysikk, fredagskollokvium, Solar Physics
Publisert 2. sep. 2021 13:35 - Sist endret 20. sep. 2021 17:47