The magnetic and spin-down properties of slowly rotating fully convective M dwarfs

Author(s)

Victor See, Louis Amard, Stefano Bellotti, Sudeshna Boro Saikia, Emma L. Brown, Jean-Francois Donati, Rim Fares, Adam J. Finley, Colin P. Folsom, Élodie M. Hébrard, Moira M. Jardine, Sandra V. Jeffers, Baptiste Klein, Lisa T. Lehmann, Stephen C. Marsden, Sean P. Matt, Matthew W. Mengel, Julien Morin, Pascal Petit, Katelyn Smith, Aline A. Vidotto, Ian A. Waite

Abstract

The evolution of the magnetism, winds and rotation of low-mass stars are

all linked. One of the most common ways to probe the magnetic properties

of low-mass stars is with the Zeeman-Doppler imaging (ZDI) technique.

The magnetic properties of partially convective stars has been

relatively well explored with the ZDI technique, but the same is not

true of fully convective stars. In this work, we analyse a sample of

stars that have been mapped with ZDI. Notably, this sample contains a

number of slowly rotating fully convective M dwarfs whose magnetic

fields were recently reconstructed with ZDI. We find that the dipolar,

quadrupolar and octupolar field strengths of the slowly rotating fully

convective stars do not follow the same Rossby number scaling in the

unsaturated regime as partially convective stars. Based on these field

strengths, we demonstrate that previous estimates of spin-down torques

for slowly rotating fully convective stars could have been

underestimated by an order of magnitude or more. Additionally, we also

find that fully convective and partially convective stars fall into

distinct sequences when comparing their poloidal and toroidal magnetic

energies.

Organisation(s)

Department of Astrophysics

Journal

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

Publication date

07-2025

Peer reviewed

Yes

Austrian Fields of Science 2012

103004 Astrophysics

Keywords

Portal url

https://ucrisportal.univie.ac.at/en/publications/bf652b67-2b84-4d87-8462-32f999e67e11