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Surface Differential Rotation of Evolved Fast Rotators

Published online by Cambridge University Press:  26 May 2016

P. Petit
Affiliation:
Observatoire Midi-Pyrénées, 14 avenue Edouard Belin, 31400 Toulouse, FranceCentro de Astrofisica da Universidade do Porto, rua das Estrelas, 4150-762 Porto, Portugal (petit@astro.up.pt)
J.-F. Donati
Affiliation:
Observatoire Midi-Pyrénées, 14 avenue Edouard Belin, 31400 Toulouse, France (donati@ast.obs-mip.fr)
G. A. Wade
Affiliation:
Royal Military College of Canada
J. D. Landstreet
Affiliation:
University of Western Ontario, Canada
T.A.A. Sigut
Affiliation:
University of Western Ontario, Canada
S.L.S. Shorlin
Affiliation:
University of Western Ontario, Canada
S. Bagnulo
Affiliation:
European Southern Observatory, Chile
T. Lüftinger
Affiliation:
Institut für Astronomie, Vienna
S. Strasser
Affiliation:
University of Minnesota, USA
J. M. Oliveira
Affiliation:
Keele University, UK
M. Aurière
Affiliation:
Observatoire Midi-Pyrénées, France
F. Lignières
Affiliation:
Observatoire Midi-Pyrénées, France
D. Mouillet
Affiliation:
Observatoire Midi-Pyrénées, France
F. Paletou
Affiliation:
Observatoire de la Côte d'Azur, France

Abstract

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Zeeman-Doppler Imaging enables one to estimate the short term temporal evolution of surface brightness and magnetic structures, under the effect of differential rotation. We present here spectropolarimetric observations secured between 1998 and 2002 for two evolved active stars: the K1 subgiant of the RS CVn system HR 1099 and the single FK Com giant HD 199178. Differential rotation is detected both from brightness and magnetic images, indicating that the rotational shear, roughly solar in magnitude for the single star, is significantly weaker in the binary system. This result suggests that tidal forces, rather than stellar evolution, could be responsible for the lower rotational shear and thus the longer spot lifetime reported for binary systems.

Information

Type
Session 2 Rotation in Relation with Abundances and Magnetic Fields
Copyright
Copyright © Astronomical Society of the Pacific 2004