Wave modes excited by photospheric p-modes & mode conversion in footpoints of coronal loops
Abstract details
id
Wave modes excited by photospheric p-modes & mode conversion in footpoints of coronal loops
Date Submitted
2019-03-07 12:19:47
Julia M.
Riedl
KU Leuven
Magnetohydrodynamic Waves and Instabilities in the Solar Atmosphere in the High-Resolution Era
Talk
J.M. Riedl , T. Van Doorsselaere , and I. C. Santamaria
Waves are ubiquitous in the solar corona and there are indications that they are excited by photospheric p-modes. However, it is unclear how p-modes in coronal loops are converted to sausage modes and transverse (kink) modes, which are observed in the corona. We aim to investigate how those wave modes are excited in the lower corona by photospheric acoustic waves. We build 3D magnetohydrostatic loop systems with different inclinations spanning from the photosphere to the lower corona. These atmospheres are then simulated with the MANCHA code, where we perturb the equilibrium with a p-mode driver at the bottom of the domain. By splitting the velocity perturbation into components longitudinal, normal, and azimuthal to the magnetic flux surfaces we can study the wave behavior. Depending on whether the driver polarization has a component perpendicular to the flux tubes or not, we find that both kink and deformed sausage waves or only sausage waves are excited. In addition, we calculate a wave conversion factor from acoustic to magnetic wave behavior by taking the ratio between the mean magnetic energy flux and the sum of the mean magnetic and acoustic energy flux and compare it to a commonly used theoretical conversion factor. We find that between magnetic field inclinations of 10° to 30° those two methods lie within 40%. For smaller inclinations the absolute deviation is smaller than 0.1.
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