KU Leuven/CmPA Seminar: The formation and heating of chromospheric fibrils in a radiation-MHD Bifrost simulation

KU Leuven Centre for mathematical Plasma-Astrophysics Seminar

Title: The formation and heating of chromospheric fibrils in a radiation-MHD Bifrost simulation

Speaker: Malcolm Druett from CmPA


Fibrils are long (500-20000 km), narrow (~180km) fibre-like features, with lifetimes of around 200-400 s. They are seen in ubiquitously on the Sun in chromospheric spectral lines.

We examine the movements of mass elements within simulated fibrils using passive tracer particles (corks) in order to understand fibril creation and destruction processes. The main process of fibrilar loading in the simulation is different to the generally accepted process of mass loading, in which waves steepen into shocks and push material upwards along the fieldlines from near their footpoints.

In the simulation twisted low lying fieldlines were destabilised and then they untwisted, lifting the material trapped above their apexes via the Lorentz force. Subsequently, the majority of the mass drained down the fieldlines towards one or both footpoints under gravity. Material with large horizontal velocities could also elevated in rising fieldlines, creating somewhat parabolic motions, but material was not generally moving upward from the footpoints of a stationary magnetic fieldline during loading.

The processes observed in the simulation are plausible additional scenarios. Criteria for observing such events are described. It is desirable that our simulations can also form more densely-packed fibrils from material fed from the base of field footpoints. Experimental parameters required to achieve this are discussed.


The following (permanent) link may be used for online access:


Date and time: Thursday, February 3, 2022 - 14:00 to 15:00


Thursday, February 3, 2022 - 14:00 to 15:00

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