Modeling X-ray emission from stellar coronae

TL;DR

This study models the magnetic fields of low-mass stars' coronae using observational data, comparing their 3D geometries and X-ray emissions under different thermal assumptions to understand their coronal structures.

Contribution

It introduces a method to construct 3D coronal magnetic field models from surface magnetograms and compares X-ray emission predictions for stars with different magnetic complexities.

Findings

Non-isothermal models fit complex fields like AB Dor well.

Isothermal assumptions are less accurate for simple fields like V374 Peg.

Complex magnetic topology influences the thermal structure of stellar coronae.

Abstract

By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a very complex field, whereas V374 Peg, which is completely convective, has a simple dipolar field. We calculate global X-ray emission measures assuming that the plasma trapped along the coronal loops is in hydrostatic equilibrium and compare the differences between assuming isothermal coronae, or by considering a loop temperature profiles. Our preliminary results suggest that the non-isothermal model works well for the complex field of AB Dor, but not for the simple field of V374 Peg.