Author name code: frogner
ADS astronomy entries on 2022-09-14
author:Frogner, Lars
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Title: Accelerated particle beams in a 3D simulation of the quiet Sun
Authors: Frogner, L.; Gudiksen, B. V.; Bakke, H.
Bibcode: 2020A&A...643A..27F
Altcode: 2020arXiv200514483F
Context. Observational and theoretical evidence suggest that beams
of accelerated particles are produced in flaring events of all sizes
in the solar atmosphere, from X-class flares to nanoflares. Current
models of these types of particles in flaring loops assume an
isolated 1D atmosphere.
Aims: A more realistic environment
for modelling accelerated particles can be provided by 3D radiative
magnetohydrodynamics codes. Here, we present a simple model for particle
acceleration and propagation in the context of a 3D simulation of
the quiet solar atmosphere, spanning from the convection zone to the
corona. We then examine the additional transport of energy introduced
by the particle beams.
Methods: The locations of particle
acceleration associated with magnetic reconnection were identified by
detecting changes in magnetic topology. At each location, the parameters
of the accelerated particle distribution were estimated from local
conditions. The particle distributions were then propagated along the
magnetic field, and the energy deposition due to Coulomb collisions
with the ambient plasma was computed.
Results: We find that
particle beams originate in extended acceleration regions that are
distributed across the corona. Upon reaching the transition region,
they converge and produce strands of intense heating that penetrate the
chromosphere. Within these strands, beam heating consistently dominates
conductive heating below the bottom of the transition region. This
indicates that particle beams qualitatively alter the energy transport
even outside of active regions.
Title: Non-thermal electrons from solar nanoflares
Authors: Bakke, Helle; Frogner, Lars; Gudiksen, Boris Vilhelm
Bibcode: 2018arXiv181112404B
Altcode:
Context. We introduce a model for including accelerated particles
in pure magnetohydrodynamics (MHD) simulations of the solar
atmosphere. Aims. We show that the method is viable and produces
results that enhance the realism of MHD simulations of the solar
atmosphere. Methods. The acceleration of high-energy electrons in
solar flares is an accepted fact, but is not included in the most
advanced 3D simulations of the solar atmosphere. The effect of the
acceleration is not known, and here we introduce a simple method to
account for the ability of the accelerated electrons to move energy
from the reconnection sites and into the dense transition zone and
chromosphere. Results. The method was only run for a short time and with
low reconnection energies, but this showed that the reconnection process
itself changes, and that there is a clear effect on the observables
at the impact sites of the accelerated electrons. Further work will
investigate the effect on the reconnection sites and the impact sites
in detail.
Title: Non-thermal electrons from solar nanoflares. In a 3D radiative
MHD simulation
Authors: Bakke, H.; Frogner, L.; Gudiksen, B. V.
Bibcode: 2018A&A...620L...5B
Altcode:
Context. We introduce a model for including accelerated particles in
pure magnetohydrodynamics (MHD) simulations of the solar atmosphere.
Aims: We show that the method is viable and produces results that
enhance the realism of MHD simulations of the solar atmosphere.
Methods: The acceleration of high-energy electrons in solar flares is an
accepted fact, but is not included in the most advanced 3D simulations
of the solar atmosphere. The effect of the acceleration is not known,
and here we introduce a simple method to account for the ability of
the accelerated electrons to move energy from the reconnection sites
and into the dense transition zone and chromosphere.
Results:
The method was only run for a short time and with low reconnection
energies, but this showed that the reconnection process itself changes,
and that there is a clear effect on the observables at the impact sites
of the accelerated electrons. Further work will investigate the effect
on the reconnection sites and the impact sites in detail.