Time-series photometric spot modeling

Free access article

Issue		A&A Volume 372, Number 1, June II 2001


Page(s)		119 - 129
Section		Formation, structure and evolution of stars
DOI		http://dx.doi.org/10.1051/0004-6361:20010362

A&A 372, 119-129 (2001)
DOI: 10.1051/0004-6361:20010362

IV. The multi-periodic K5Ve binary V833 Tauri

K. Oláh¹, K. G. Strassmeier^{2, 3}, Zs. Kovári¹ and E. F. Guinan⁴

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

(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 $\approx$ 70 years, 6.5 years and 2.4 years. Using V and $I_{\rm C}$ -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 $1230 {\rm K}\pm270$ K relative to the photosphere is found. This value agrees with previous results from TiO modeling ( $1330 {\rm K}\pm110$ 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 $UBV(RI)_{\rm C}$ 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 $V(RI)_{\rm C}$ bands. The flare characteristics are compared to another, 100-times smaller flare observed earlier in 1983.

Key words: stars: activity -- stars: atmospheres -- stars: late-type -- stars: individual: V833 Tau -- stars: binaries: close

Offprint request: K. Oláh, olah@konkoly.hu

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