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Cycle times of early M dwarf stars: mean field models versus observations

Published online by Cambridge University Press:  24 September 2020

Manfred Küker Open the ORCID record for Manfred Küker [Opens in a new window] ,
Günther Rüdiger ,
Katalin Oláh  and
Klaus G. Strassmeier
Manfred Küker
Affiliation:
Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany emails: mailto:mkueker@aip.de, mailto:gruediger@aip.de, mailto:kstrassmeier@aip.de
Günther Rüdiger
Affiliation:
Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany emails: mailto:mkueker@aip.de, mailto:gruediger@aip.de, mailto:kstrassmeier@aip.de
Katalin Oláh
Affiliation:
Konkoly Observatory, Budapest Hungary email: mailto:olahkatalin5@gmail.com
Klaus G. Strassmeier
Affiliation:
Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany emails: mailto:mkueker@aip.de, mailto:gruediger@aip.de, mailto:kstrassmeier@aip.de
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Abstract

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Observations of early-type M stars suggest that there are two characteristic cycle times, one of order one year for fast rotators (Prot < 1 day) and another of order four years for slower rotators. For a sample of fast-rotating stars, the equator-to-pole differences of the rotation rates up to 0.03 rad d−1 are also known from Kepler data. These findings are well-reproduced by mean field models. These models predict amplitudes of the meridional flow, from which the travel time from pole to equator at the base of the convection zone of early-type M stars can be calculated. As these travel times always exceed the observed cycle times, our findings do not support the flux transport dynamo.

Keywords

Stars: late-typestars: magnetic fieldstars: activitymagnetohydrodynamics (MHD)turbulence
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 15 , Symposium S354: Solar and Stellar Magnetic Fields: Origins and Manifestations , June 2019 , pp. 116 - 119
Copyright
© International Astronomical Union 2020

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