Heidelberg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

EP: Fachverband Extraterrestrische Physik

EP 12: Sun and Heliosphere

EP 12.10: Vortrag

Freitag, 25. März 2022, 13:40–13:50, EP-H1

Coronal Magnetic Field Extrapolation Using a Specific Family of Analytical 3D Magnetohydrostatic Equilibria - Practical Aspects — •Lilli Nadol and Thomas Neukirch — University of St Andrews, Scotland, UK

With current observational methods it is not possible to determine the magnetic field in the solar corona accurately. Hence, coronal magnetic field models have to rely on extrapolation methods using photospheric magnetograms as boundary conditions. In recent years, due to the increased resolution of observations and the need to resolve non-forcefree lower regions of the solar atmosphere, there have been efforts to use magnetohydrostatic (MHS) field models instead of force-free extrapolation methods. Although numerical methods to calculate MHS solutions can deal with non-linear problems more accurately, analytical 3D MHS equilibria can also be used as a numerically "cheaper" method.

We discuss a family of analytical MHS equilibria that allows for a transition from a non-force-free to a force-free region. The solution involves hypergeometric functions. While routines for the calculation of these are available, this can affect the speed and accuracy of the calculations. We look into the asymptotic behaviour of this solution in order to approximate it through exponential functions to improve the numerical efficiency. We present an illustrative example by comparing field line profiles, density and pressure differences between the exact solutions and the asymptotic solution.