Large-scale magnetic topologies of mid M dwarfs

J. Morin, J. F. Donati, P. Petit, X. Delfosse, T. Forveille, L. Albert, M. Aurière, R. Cabanac, B. Dintrans, R. Fares, T. Gastine, M. M. Jardine, F. Lignières, F. Paletou, J. C.Ramirez Velez, S. Théado

Research output: Contribution to journalArticlepeer-review

291 Citations (Scopus)

Abstract

We present in this paper, the first results of a spectropolarimetric analysis of a small sample (∼20) of active stars ranging from spectral type M0 to M8, which are either fully convective or possess a very small radiative core. This study aims at providing new constraints on dynamo processes in fully convective stars. This paper focuses on five stars of spectral type ∼M4, i.e. with masses close to the full convection threshold (≃0.35 M ), and with short rotational periods. Tomographic imaging techniques allow us to reconstruct the surface magnetic topologies from the rotationally modulated time-series of circularly polarized profiles. We find that all stars host mainly axisymmetric large-scale poloidal fields. Three stars were observed at two different epochs separated by ∼1 yr; we find the magnetic topologies to be globally stable on this time-scale. We also provide an accurate estimation of the rotational period of all stars, thus allowing us to start studying how rotation impacts the large-scale magnetic field.

Original languageEnglish
Pages (from-to)567-581
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume390
Issue number2
DOIs
Publication statusPublished - Oct 2008
Externally publishedYes

Keywords

  • Stars: activity
  • Stars: low-mass, brown dwarfs
  • Stars: magnetic fields
  • Stars: rotation
  • Techniques: polarimetric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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