Abstract
Aims: We investigate the temporal spot evolution of the K-giant
component in the RS CVn-type binary system ¿ Andromedae to
establish its surface differential rotation. Methods: Doppler
imaging was used to study three slightly overlapping spectroscopic
datasets, which were obtained independently at three different observing
sites. Each dataset covers one full stellar rotation with good phase
coverage, which results in a continuous coverage of almost three stellar
rotations (Prot = 17.8 d). Therefore, these data are
well-suited for reconstructing surface temperature maps and studying
temporal evolution in spot configurations. Surface differential rotation
was measured by the means of cross-correlation of all possible image
pairs. Results: The individual Doppler reconstructions agree well
in the revealed spot pattern, recovering numerous low-latitude spots
with temperature contrasts of up to ¿1000 K with respect to the
unspotted photosphere, and also an asymmetric polar cap that is
diminishing with time. Our detailed cross-correlation study consistently
indicates solar-type differential rotation with an average surface shear
¿ ¿ 0.055, in agreement with former results.
Based on observations collected using the Bernard Lyot Telescope at Pic
du Midi Observatory; the 1.93-m telescope at Haute-Provence Observatory,
France; and the 8.2-m Kueyen telescope (VLT/UT2) of the European
Southern Observatory, Chile (Prg. 081.D-0216(A)).
Original language | English |
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Pages (from-to) | 50 |
Journal | Astronomy & Astrophysics |
Volume | 539 |
Publication status | Published - 1 Mar 2012 |