Dynamo-generated magnetic fields in fast rotating single giants

TL;DR

This study reports the detection of magnetic fields in fast rotating single giant stars, including the first direct detection in an evolved M-giant, supporting the presence of an alpha-omega dynamo mechanism.

Contribution

It presents the first direct magnetic field detection in an evolved M-giant and demonstrates the operation of an alpha-omega dynamo in these stars.

Findings

Six magnetic field detections in fast rotating giants

First direct magnetic detection in an evolved M-giant (EK Boo)

Magnetic fields explained by alpha-omega dynamo model

Abstract

Red giants offer a good opportunity to study the interplay of magnetic fields and stellar evolution. Using the spectro-polarimeter NARVAL of the Telescope Bernard Lyot (TBL), Pic du Midi, France and the LSD technique, we began a survey of magnetic fields in single G-K-M giants. Early results include 6 MF-detections with fast rotating giants, and for the first time a magnetic field was detected directly in an evolved M-giant: EK Boo. Our results could be explained in the terms of $\alpha$--$\omega$ dynamo operating in these giants.