Large-scale magnetic topologies of late M dwarfs

Details Large-scale magnetic topologies of late M dwarfs Large-scale magnetic topologies of late M dwarfs

2010-05-30

arxiv.org/abs/1005.5552v2

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

26 pages, 16 figures, 9 tables, 11 tables in appendix. Accepted for publication in MNRAS

Scientific paper

10.1111/j.1365-2966.2010.17101.x

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 (Donati et al. 2008b; Morin et al. 2008b) 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 polarised profiles of 6 stars, in order to infer their large-scale magnetic topologies. For 3 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 2 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 2 categories in the mass-rotation plane. We also report marginal detection of a large-scale magnetic field on the M8 star VB 10 featuring a significant toroidal axisymmetric component, whereas no field is detectable on VB 8 (M7).

Affiliated with

Also associated with

No associations

Rating

Large-scale magnetic topologies of late M dwarfs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Large-scale magnetic topologies of late M dwarfs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Large-scale magnetic topologies of late M dwarfs will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-162128