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 quasi-sinusoidal modulation of its observed eclipse arrival times. The O-Cs have been analyzed for the ``light-time'' effect that arises from the gravitational influence of a tertiary companion. The presence of a third body causes the relative distance of the eclipsing pair to the Earth to change as it orbits the barycenter of the triple system. The result of the analysis of the eclipse times yields a light-time semi-amplitude of 137.2+/-12.0 s, an orbital period of P3 = 30.5+/-1.6 yr and an eccentricity of e3 = 0.31+/-0.04. The mass of the tertiary component is M3 sin i3 = 0.0393+/-0.0038 Mo when a total mass of 1.61+/-0.06 Mo for V471 Tau is adopted. For orbital inclinations i3 > 35 deg, the mass of the third body would be below the stable hydrogen burning limit of M = 0.07 Mo and it thus would be a brown dwarf. In the next several years (near maximum elongation), it should be feasible to obtain IR images and spectra of V471 Tau C that, when combined with the known mass, age, distance, and Fe/H, will serve as a benchmark for understanding the physical properties and evolution of brown dwarfs.

Main Author: Guinan, Edward F.
Other Authors: Ribas, Ignasi.
Language: English
Published: 2000
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