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 language | English |
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Pages (from-to) | 567-581 |
Number of pages | 15 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 390 |
Issue number | 2 |
DOIs | |
Publication status | Published - Oct 2008 |
Externally published | Yes |
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