SIMBAD references

2010MNRAS.407.2269M - Mon. Not. R. Astron. Soc., 407, 2269-2286 (2010/October-1)

Large-scale magnetic topologies of late M dwarfs.


Abstract (from CDS):

We present here the final results of the first spectropolarimetric survey of a small sample of active M dwarfs, aimed at providing observational constraints on dynamo action on both sides of the full-convection threshold (spectral type M4). Our two previous studies were focused on early and mid M dwarfs. The present paper examines 11 fully convective late M dwarfs (spectral types M5-M8). Tomographic imaging techniques were applied to time-series of circularly polarized profiles of six stars, in order to infer their large-scale magnetic topologies. For three other stars we could not produce such magnetic maps, because of low variability of the Stokes V signatures, but were able to derive some properties of the magnetic fields.

We find two distinct categories of magnetic topologies: on the one hand strong axisymmetric dipolar fields (similar to mid M dwarfs), and on the other hand weak fields generally featuring a significant non-axisymmetric component, and sometimes a significant toroidal one. Comparison with unsigned magnetic fluxes demonstrates that the second category of magnetic fields shows less organization (less energy in the large scales), similarly to partly convective early M dwarfs. Stars in both categories have similar stellar parameters, our data do not evidence a separation between these two categories in the mass-rotation plane.

We also report marginal detection of a large-scale magnetic field on the M8 star VB10 featuring a significant toroidal axisymmetric component, whereas no field is detectable on VB8 (M7).

Abstract Copyright: © 2010 The Authors. Journal compilation © 2010 RAS

Journal keyword(s): techniques: polarimetric - stars: low-mass - stars: magnetic field - stars: rotation

VizieR on-line data: <Available at CDS (J/MNRAS/407/2269): stars.dat table1.dat tables.dat>

Status at CDS:  

Simbad objects: 26

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