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Rotation & differential rotation of the active Kepler stars

Published online by Cambridge University Press:  07 August 2014

Timo Reinhold
Affiliation:
Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany email: [email protected]
Ansgar Reiners
Affiliation:
Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany email: [email protected]
Gibor Basri
Affiliation:
Astronomy Department, University of California, Berkeley, CA 94720, USA email: [email protected]
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Abstract

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Stellar rotation is a well-known quantity for tens of thousands of stars. In contrast, differential rotation (DR) is only known for a handful of stars because DR cannot be measured directly. We present rotation periods for more than 24,000 active stars in the Kepler field. Thereof, more than 18,000 stars show a second period, which we attribute to surface differential rotation. Our rotation periods are consistent with previous measurements and the theory of magnetic braking. Our results on DR paint a rather different picture: The temperature dependence of the absolute shear δΩ is split into two groups separated around 6000 K. For the cooler stars δΩ only slightly increases with temperature, whereas stars hotter than 6000 K show large scatter. This is the first time that DR has been measured for such a large number of stars.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

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