Issue |
A&A
Volume 384, Number 1, MarchII 2002
|
|
---|---|---|
Page(s) | 155 - 162 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20011801 | |
Published online | 15 March 2002 |
On the feasibility of the detection of differential rotation in stellar absorption profiles
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
Corresponding author: A. Reiners, areiners@hs.uni-hamburg.de
Received:
24
September
2001
Accepted:
12
December
2001
Stellar differential rotation invokes subtle effects on
line absorption profiles which can be best studied in the Fourier
domain. Detailed calculations of the behavior of Fourier
transformed profiles with respect to varying differential
rotation, limb darkening and inclination angles are presented.
The zero positions of the Fourier transform are found to be very
good tracers of differential rotation. The ratio of the first two
zero positions can be easily measured and
is a reliable parameter to deduce the amount of differential
rotation. It is shown that solar-like differential rotation
(equatorial regions have larger angular velocity then polar
regions) has an unambigious signature in the Fourier domain and
that in certain cases it can easily be distinguished from limb
darkening effects. A simple procedure is given allowing the
determination of the amount of differential rotation by the
knowledge of the first two zero positions of a line profile's
Fourier transform alone (i.e., without the need for thorough
atmospheric modelling), under the assumption of a linear limb
darkening law with a limb darkening coefficient of
.
Key words: stars: rotation / line: profiles
© ESO, 2002
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