Ph.D. defence: George Cherry, Institute of Theoretical Astrophysics, UiO
Schedule
Wed Sep 03 2025 at 01:15 pm to 03:30 pm
UTC+02:00Location
Institute of Theoretical Astrophysics, University of Oslo | Oslo, OS
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Title: «Quantifying energy transfer in the solar atmosphere»
Just like in the oceans and atmosphere on Earth, a vast range of waves exist in the plasma of the solar atmosphere. Understanding the transfer of energy via these magnetohydrodynamic (MHD) waves has important implications for our theory on the heating of the upper solar atmosphere (coronal heating) and the prediction of geomagnetic storms by monitoring the solar wind. Despite extensive theory and simulations, the detection of waves in realistic simulations still presents a large challenge, due to wave interaction, conversion, dissipation and numerical artefacts: it is like finding a needle in a haystack full of needle-like objects.
Through the development of a new method for detecting wave activity in simulations, I have demonstrated that different magnetic structures can inhibit and prohibit the propagation of waves, including the dominant oscillations at 3.5 mHz and 5 mHz, which have previously been detected as “global modes” in both observations and simulations. Specifically, we find that twisted magnetic features called swirls enable the transport of magnetoacoustic waves at 3.5 mHz waves to the upper atmosphere, whilst in the absence of swirls, plasma motions in the chromosphere enhance the wave activity at 5 mHz. These results lead to exciting prospects in the realm of quantifying the energy deposit to the upper atmosphere in different solar regimes.
Image: Sunrise over the North Sea. Credits: George Cherry
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Trial Lecture: «The magnetic connection of the Sun to the solar wind»
Time and Place: September 3, 2025 10:15 AM CEST, Auditorium 209 Svein Rosselands hus.
More information can be found on this webpage: https://www.mn.uio.no/astro/english/research/news-and-events/events/disputations/2025/George_Cherry
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Where is it happening?
Institute of Theoretical Astrophysics, University of Oslo, Sognsveien 77B, 0855 Oslo, Norge, Oslo, NorwayEvent Location & Nearby Stays:
