Zeeman Broadening in Optical Stokes I of Solar-like Stars

TL;DR

This study investigates the detectability of Zeeman broadening in optical spectra of solar-like stars to infer their magnetic fields, highlighting the challenges and uncertainties involved in measurement.

Contribution

The paper demonstrates the potential and limitations of using high-quality optical data and spectral line inversion to measure magnetic fields in solar-like stars.

Findings

Zeeman broadening can be detected with high-quality optical spectra.

Measurement uncertainties are large and model-dependent.

Spectral blends complicate magnetic field quantification.

Abstract

We present our analysis aimed at inferring average magnetic fields in slowly-rotating solar-like stars. Using the spectral line inversion code SPINOR, we perform high-accuracy line profile fitting and investigate whether Zeeman broadening can be reliably detected in optical data of unprecedented quality. We argue that our usage of both high- and low-g_{eff} lines does provide a certain sensitivity to magnetic fields that may, indeed, be detected. However, the measurement is subject to a model dependence and prone to ambiguities, e.g. due to spectral blends. Hence, while a field may be successfully recovered, the quantification of this field is subject to large uncertainties, even for the highest-quality optical data.