Magneto-static modelling of the mixed plasma Beta solar atmosphere based on SUNRISE/IMaX data

TL;DR

This paper develops a magneto-static model of the solar atmosphere's magnetic field using high-resolution SUNRISE/IMaX data, accounting for plasma beta effects and forces in the photosphere and chromosphere.

Contribution

It introduces a linear magneto-static modeling approach that includes pressure and gravity forces, extending magnetic field modeling into the mixed plasma beta environment.

Findings

Magnetic field becomes nearly force-free above 2 Mm height.

The linear model captures the interface region between photosphere and corona.

Limitations of the linear approach are discussed with prospects for non-linear extension.

Abstract

Our aim is to model the 3D magnetic field structure of the upper solar atmosphere, including regions of non-negligible plasma beta. We use high-resolution photospheric magnetic field measurements from SUNRISE/IMaX as boundary condition for a magneto-static magnetic field model. The high resolution of IMaX allows us to resolve the interface region between photosphere and corona, but modelling this region is challenging for the following reasons. While the coronal magnetic field is thought to be force-free (the Lorentz-force vanishes), this is not the case in the mixed plasma $\beta$ environment in the photosphere and lower chromosphere. In our model, pressure gradients and gravity forces are taken self-consistently into account and compensate the non-vanishing Lorentz-force. Above a certain height (about 2 Mm) the non-magnetic forces become very weak and consequently the magnetic field becomes almost force-free. Here we apply a linear approach, where the electric current density consists of a superposition of a field-line parallel current and a current perpendicular to the Sun's gravity field. We illustrate the prospects and limitations of this approach and give an outlook for an extension towards a non-linear model.