2013A&A...549L...5G


C.D.S. - SIMBAD4 rel 1.7 - 2019.07.21CEST15:56:43

2013A&A...549L...5G - Astronomy and Astrophysics, volume 549, L5-5 (2013/1-1)

What controls the magnetic geometry of M dwarfs?

GASTINE T., MORIN J., DUARTE L., REINERS A., CHRISTENSEN U.R. and WICHT J.

Abstract (from CDS):

Observations of rapidly rotating M dwarfs show a broad variety of large-scale magnetic fields encompassing dipole-dominated and multipolar geometries. In dynamo models, the relative importance of inertia in the force balance, which is quantified by the local Rossby number, is known to have a strong impact on the magnetic field geometry. We aim to assess the relevance of the local Rossby number in controlling the large-scale magnetic field geometry of M dwarfs. We have explored the similarities between anelastic dynamo models in spherical shells and observations of active M-dwarfs, focusing on field geometries derived from spectropolarimetric studies. To do so, we constructed observation-based quantities aimed to reflect the diagnostic parameters employed in numerical models. The transition between dipole-dominated and multipolar large-scale fields in early to mid M dwarfs is tentatively attributed to a Rossby number threshold. We interpret late M dwarfs magnetism to result from a dynamo bistability occurring at low Rossby number. By analogy with numerical models, we expect different amplitudes of differential rotation on the two dynamo branches.

Abstract Copyright:

Journal keyword(s): dynamo - magnetohydrodynamics (MHD) - stars: magnetic field - stars: rotation - stars: low-mass - brown dwarfs

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 BD+16 2708 Fl* 14 54 29.2359453437 +16 06 03.798840236 12.86 11.686 10.150 9.116 7.872 M3V 230 1
2 G 208-45 Er* 19 53 55.1388332012 +44 24 54.144273353   15.97 13.99 14.3 10.27 M6V 152 0
3 V* V374 Peg Fl* 22 01 13.1233106147 +28 18 24.913041858       11.602   M3.5Ve 153 0

    Equat.    Gal    SGal    Ecl

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2019.07.21-15:56:43

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