Issue |
A&A
Volume 412, Number 3, December IV 2003
|
|
---|---|---|
Page(s) | 813 - 819 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20034255 | |
Published online | 08 December 2003 |
Differential rotation in rapidly rotating F-stars *,**
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: areiners,jschmitt@hs.uni-hamburg.de
Corresponding author: A. Reiners, areiners@hs.uni-hamburg.de
Received:
2
September
2003
Accepted:
10
September
2003
We obtained high quality spectra of 135 stars of spectral
types F and later and derived “overall” broadening functions in
selected wavelength regions utilizing a Least Squares Deconvolution (LSD) procedure. Precision values of the projected rotational
velocity were derived from the first zero of the Fourier transformed profiles and the shapes of the profiles were
analyzed for effects of differential rotation. The broadening
profiles of 70 stars rotating faster than
km s-1 show no indications of multiplicity nor of
spottedness. In those profiles we used the ratio of the first two
zeros of the Fourier transform
to search for deviations
from rigid rotation. In the vast majority the profiles were found
to be consistent with rigid rotation. Five stars were found to have
flat profiles probably due to cool polar caps, in three stars cuspy
profiles were found. Two out of those three cases may be due to
extremely rapid rotation seen pole on, only in one case (
km s-1) is solar-like differential rotation the most
plausible explanation for the observed profile. These results
indicate that the strength of differential rotation diminishes in
stars rotating as rapidly as
km s-1.
Key words: stars: rotation / stars: late-type / stars: activity / methods: data analysis / line: profiles
© ESO, 2003
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