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Astron. Astrophys. 323, 801-808 (1997)

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Testing the stability and reliability of starspot modelling

Zs. Kvári 1 and J. Bartus 1, 2

1 Konkoly Observatory of the Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest, Hungary (kovari@buda.konkoly.hu,bartus@buda.konkoly.hu)
2 Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, A-1180 Wien, Austria (bartus@astro.ast.univie.ac.at)

Received 8 November 1995 / Accepted 15 January 1997


Since the mid 70's different starspot modelling techniques have been used to describe the observed spot variability on active stars. Spot positions and temperatures are calculated by application of surface integration techniques or solution of analytic equations on observed photometric data. Artificial spotted light curves were generated, by use of the analytic expressions of Budding (1977), to test how the different constraints like the intrinsic scatter of the observed data or the angle of inclination affects the spot solutions. Counteractions between the different parameters like inclination, latitude and spot size were also investigated. The results of re-modelling the generated data were scrutinized statistically. It was found, that (1) [FORMULA] of photometric accuracy is required to recover geometrical spot parameters within an acceptable error box; (2) even a [FORMULA] error in unspotted brightness substantially affects the recovery of the original spot distribution; (3) especially at low inclination, under- or overestimation of inclination by [FORMULA] leads to an important systematic error in spot latitude and size; (4) when the angle of inclination [FORMULA] photometric spot modelling is unable to provide satisfactory information on spot location and size.

Key words: stars: activity; imaging; late-type; starspots – methods: data analysis


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© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998