Time-series photometric spot modeling

IV. The multi-periodic K5Ve binary V833 Tauri

¹ Konkoly Observatory of the Hungarian Academy of Sciences, 1525 Budapest, Hungary e-mail: kovari@konkoly.hu
² Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: KStrassmeier@aip.de
³ Institute for Astronomy, University of Vienna, 1180 Vienna, Austria
⁴ Dept. of Astronomy and Astrophysics, Villanova University, Villanova, PA 19085, USA e-mail: edward.guinan@villanova.edu

Corresponding author: K. Oláh, olah@konkoly.hu

Received: 27 November 2000
Accepted: 7 March 2001

Abstract

We analysed all the existing photometric observations of V833 Tau and found long-term variability on time scales of ≈70 years, 6.5 years and 2.4 years. Using V and I_C-band data from 1990-2000, we obtained starspot surface distributions from 20 suitable light curves. We found that the spot-area changes generally follow the long-term light variations. Spot temperatures are determined for each of the datasets and an average value of K relative to the photosphere is found. This value agrees with previous results from TiO modeling ( K). Small scale spot temperature and area changes are recovered during 1997-1999, that we explain with a variable spot/faculae ratio. A powerful flare in was observed in 1993 November. A 10 000 K fit yielded a total emitted flare energy of more than 10³⁴ ergs from an area of about 1.3% of the stellar surface, 60% of it in the bands. The flare characteristics are compared to another, 100-times smaller flare observed earlier in 1983.