Magnetic fields in M-dwarfs: quantitative results from detailed spectral synthesis in FeH lines

TL;DR

This paper presents detailed spectral synthesis modeling of FeH lines to quantitatively measure magnetic fields in M-dwarfs, providing insights into stellar magnetism and dynamo processes in these cool stars.

Contribution

It introduces a novel spectral synthesis approach to accurately analyze magnetic fields in M-dwarfs using FeH lines, overcoming previous limitations.

Findings

FeH lines are effective magnetic field probes

Quantitative magnetic field measurements achieved

Enhanced understanding of stellar magnetism in M-dwarfs

Abstract

Strong surface magnetic fields are ubiquitously found in M-dwarfs with mean intensities on the order of few thousand Gauss-three orders of magnitude higher than the mean surface magnetic field of the Sun. These fields and their interaction with photospheric convection are the main source of stellar activity, which is of big interest to study links between parent stars and their planets. Moreover, the understanding of stellar magnetism, as well as the role of different dynamo-actions in particular, is impossible without explaining magnetic fields in M-dwarfs. Measuring magnetic field intensities and geometries in such cool objects, however, is strongly limited to our ability to simulate the Zeeman effect in molecular lines. In this work, we present quantitative results of modelling and analysis of the magnetic fields in selected M-dwarfs in FeH Wing-Ford lines and strong atomic lines. Some particular FeH lines are found to be the excellent probes of the magnetic field.