Document Type

Article

Publication Date

3-1997

Abstract

HD 202908=ADS 14839 is a spectroscopic-visual triple system consisting of three solar-type stars. Eighteen years of spectroscopic observations including coverage of the recent periastron of 1987 January plus visual and speckle observations, the latter covering roughly the same interval as the radial velocities, have been used to obtain a simultaneous three-dimensional orbital solution. The short-period pair, Aa and Ab, has an orbital period of 3.9660465 days and a small but real eccentricity of 0.0033. The visual pair, A and B, has an orbital period of 78.5 yr and an eccentricity of 0.865. The solution yields masses for all three stars with uncertainties of about 2%, and the distance to the system with an uncertainty of 1.3%. Spectroscopic luminosity ratios, combined with the above distance, yield absolute magnitudes with uncertainties of about 0.1 mag. Thus the system provides three well-determined points on the mass- luminosity relationship. The inclinations of the short- and long-period orbits differ by 29°, making the orbits noncoplanar. Assuming synchronous rotation, the rotational and orbital axes of the short-period pair are aligned. The chromospheric emission, lithium abundance, and projected rotational velocity of component B indicate that the system is quite young, probably about the age of the Hyades Cluster. A comparison with theoretical evolutionary tracks supports such a conclusion.

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