Lars Frogner

Room 213

Available hours 08:00-16:00

Username

Visiting address Sem Sælandsvei 13 Svein Rosselands hus 0371 Oslo

Press photo

Academic interests

My research is mainly concerned with numerical modelling of the solar atmosphere, in particular the origin, behaviour and effect of accelerated particles. I am generally interested in a range of topics in software development, including numerical simulations and computer graphics.

Courses taught

AST2000 - Introduction to astrophysics (teaching assistant)

Background

I completed a bachelor's degree in Physics, Astronomy and Meteorology in 2016 and a master's degree in Astronomy in 2018, both at the University of Oslo.

Tags: Astronomy and Astrophysics, Solar Physics, Simulations, Computational Astrophysics

Frogner, Lars & Gudiksen, Boris Vilhelm (2024). Accelerated particle beams in a 3D simulation of the quiet Sun: Effects of advanced beam propagation modelling. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 683. doi: 10.1051/0004-6361/202348457. Full text in Research Archive
Bakke, Helle; Frogner, Lars; Rouppe van der Voort, Luc; Gudiksen, Boris Vilhelm & Carlsson, Mats (2023). Accelerated particle beams in a 3D simulation of the quiet Sun: Lower atmospheric spectral diagnostics. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202346765. Full text in Research Archive
Frogner, Lars; Gudiksen, Boris Vilhelm & Bakke, Helle (2020). Accelerated particle beams in a 3D simulation of the quiet Sun. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 643. doi: 10.1051/0004-6361/202038529. Full text in Research Archive Show summary
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.
Bakke, Helle; Frogner, Lars & Gudiksen, Boris Vilhelm (2018). Non-thermal electrons from solar nanoflares In a 3D radiative MHD simulation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 620. doi: 10.1051/0004-6361/201834129. Full text in Research Archive

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Frogner, Lars & Gudiksen, Boris Vilhelm (2023). Accelerated particles in the solar atmosphere.
Frogner, Lars (2022). Accelerated particle beams in a 3D simulation of the quiet Sun.
Gudiksen, Boris Vilhelm; Frogner, Lars; Bakke, Helle & Clemmensen, Frederik (2020). Accelerated particles in the solar atmosphere .
Gudiksen, Boris Vilhelm; Frogner, Lars & Bakke, Helle (2020). Accelerated particles in the solar atmosphere.
Frogner, Lars (2020). Accelerated particles in the solar atmosphere.
Frogner, Lars; Gudiksen, Boris Vilhelm & Carlsson, Mats (2024). Modelling accelerated particles in the solar atmosphere. Faculty of Mathematics and Natural Sciences. ISSN 1501-7710.

View all works in Cristin

Published Oct. 1, 2020 4:40 PM - Last modified Oct. 1, 2020 4:40 PM