The best brown dwarf yet? A companion to the Hyades eclipsing binary V471 Tauri

We have carried out an analysis of about 160 eclipse timings spanning over 30 years of the Hyades eclipsing binary V471 Tauri that shows a long-term q uasi-sinusoidal modulation of its observed eclipse arrival times. The O - C values have been analyzed for the "light-time" effect that arises from the gravitational influence of a tertiary companion. The presence of a third b ody causes the relative distance of the eclipsing pair to the Earth to chan ge as it orbits the barycenter of the triple system. The result of the anal ysis of the eclipse times yields a light-time semiamplitude of 137.2 +/- 12 .0 s, an orbital period of P-3 = 30.5 +/- 1.6 yr, and an eccentricity of e( 3) = 0.31 +/- 0.04. The mass of the tertiary component is M-3 sin i3 simila r or equal to 0.0393 +/- 0.0038 M. when a total mass of 1.61 +/- 0.006 M. f or V471 Tau is adopted. For orbital inclinations i(3) greater than or simil ar to 35 degrees, the mass of the third body would be below the stable hydr ogen-burning limit of M approximate to 0.07 M., and thus it would be a brow n dwarf. In the next M several years (near maximum elongation), it should b e feasible to obtain IR images and spectra of V471 Tau C that, when combine d with the known mass, age, distance, and [Fe/H], will serve as a benchmark for understanding the physical properties and evolution of brown dwarfs.