A&A 430, L17-L20 (2005)
DOI: 10.1051/0004-6361:200400120
Letter
Strong latitudinal shear in the shallow convection zone of a rapidly rotating A-star
A. Reiners1, 2, M. Hünsch3, M. Hempel4 and J. H. M. M. Schmitt21 Astronomy Department, University of California, Berkeley, CA 94720, USA
e-mail: areiners@astron.berkeley.edu
2 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: jschmitt@hs.uni-hamburg.de
3 Institut für Theoretische Physik und Astrophysik, Leibnizstrasse 15, 24098 Kiel, Germany
e-mail: mhuensch@astrophysik.uni-kiel.de
4 Astrophysikalisches Institut Jena, Schillergäßchen 2-3, 07745 Jena, Germany
e-mail: marc@astro.uni-jena.de
(Received 2 November 2004 / Accepted 9 December 2004 )
Abstract
We have derived the mean broadening profile of the star
V 102 in the region of the open cluster IC 4665 from high
resolution spectroscopy. At a projected equatorial rotation velocity
of
km s
-1 we find strong
deviation from classical rotation. We discuss several scenarios, the
most plausible being strong differential rotation in latitudinal
direction. For this scenario we find a difference in angular
velocity of
rad d
-1
(
. From the H
line we
derive a spectral type of A9 and support photometric measurements
classifying IC 4665 V 102 as a non-member of IC 4665. At such early
spectral type this is the strongest case of differential rotation
observed so far. Together with three similar stars, IC 4665 V 102
seems to form a new class of objects that exhibit extreme
latitudinal shear in a very shallow convective envelope.
Key words: stars: rotation -- line: profiles -- stars: individual: IC 4665 V 102/P35 -- clusters: individual: IC 4665
SIMBAD Objects
© ESO 2005