Multiple views of magnetism in cool stars

TL;DR

This paper reviews multiple observational methods for studying magnetic fields in cool stars, highlighting their strengths, limitations, and the importance of combining different proxies to better understand stellar magnetism.

Contribution

It provides a comprehensive overview of current techniques and their evolution in the study of stellar magnetic fields, emphasizing the integration of various approaches.

Findings

Different methods offer complementary insights into stellar magnetism.

Coupling multiple proxies enhances understanding of magnetic activity.

Current techniques have specific strengths and limitations.

Abstract

Magnetic fields are regarded as a crucial element for our understanding of stellar physics. They can be studied with a variety of methods which provide complementary - and sometimes contradictory - information about the structure, strength and dynamics of the magnetic field and its role in the evolution of stars. Stellar magnetic fields can be investigated either with direct methods based on the Zeeman effect or through the observation of activity phenomena resulting from the interaction of the field with the stellar atmosphere. In this Cool Stars XVII Splinter Session we discussed the results obtained by the many ongoing studies of stellar activity and direct studies of surface magnetic fields, as well as the state- of-the-art techniques on which they are based. We show the strengths and limitations of the various approaches currently used and to point out their evolution as well as the interest of coupling various magnetism and activity proxies.