EDP Sciences
Free access
Volume 388, Number 3, June IV 2002
Page(s) 1120 - 1123
Section Instruments, observational techniques and data processing
DOI http://dx.doi.org/10.1051/0004-6361:20020564

A&A 388, 1120-1123 (2002)
DOI: 10.1051/0004-6361:20020564

Can star spots mimic differential rotation?

A. Reiners and J. H. M. M. Schmitt

Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

(Received 30 January 2002 / Accepted 20 March 2002 )

The search for stellar differential rotation in Fourier-transformed profiles utilizes subtle deviations from the standard rotation profile. We investigate the influence of stellar spots on the results obtained with the Fourier Transform Method. Different spot configurations, especially polar spots, are examined, and their influence on Fourier-transformed line profiles studied. We found that polar spots cannot mimic solar-like differential rotation and are thus not critical for the use of the Fourier Transform Method. Although not indicated by Doppler imaging, other configurations may occur on stellar surfaces and their influence on the analysis is discussed. A symmetric distribution of spots in an activity belt leads - in a small region of the parameter space - to line profiles that are very similar to the signatures produced by differential rotation.

Key words: starspots -- stars: rotation

Offprint request: A. Reiners, areiners@hs.uni-hamburg.de

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