EDP Sciences
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Volume 395, Number 2, November IV 2002
Page(s) 587 - 593
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20021317

A&A 395, 587-593 (2002)
DOI: 10.1051/0004-6361:20021317

Long-term photometry of the near-contact detached binary GR Tauri

X. B. Zhang, R. X. Zhang and M. J. Fang

National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China

(Received 3 June 2002 / Accepted 9 September 2002 )

We present photometric observations of the eclipsing binary GR Tau made in 1985, 1993, 1998, 2000 and 2001. New times of minima and ephemerides are given. Based on a statistical analysis of the times of minima obtained by photoelectric and CCD photometry, the orbital period of the system is found to be decreasing with a rate of $\Delta P/P = 3.27 \times10^{-10}$ during the past decades. An assumed hot spot on the trailing hemisphere of the secondary enables us to reconstruct the peculiar asymmetry of the distorted light curves. The photometric solution with the Wilson-Devinney code reveals that GR Tau is a near-contact detached system with the two components almost filling their respective critical Roche lobes. The photometric mass ratio turns out to be q=0.22, and the masses and radii are derived for the components as $M_{1}=1.42\pm 0.18~ M_{\odot}$, $M_{2}=0.31\pm 0.04~ M_{\odot}$, $R_{1}=1.47\pm 0.19~ R_{\odot}$ and $R_{2}=0.70\pm 0.09~ R_{\odot}$. The authors discuss the possible evolutionary status of the component stars and the probable nature of the assumed hot spot.

Key words: stars: binaries: eclipsing -- stars: individual: GR Tau

Offprint request: X. Zhang, xzhang@bao.ac.cn

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