Absolute dimensions of eclipsing binaries. XVI. V1031 Orionis.

The high-dispersion spectroscopic observations of the triple system V 1031 Orionis are presented, including catalog data, radial-velocity observations, spectral lines, and orbital elements. Photometric data are discussed with emphasis on the method of observation, ephemeris, and photometric elements. Absolute dimensions are analyzed, and the evolutionary models of the system are outlined, along with rotation of the components. It is noted that despite the complications produced by the presence of a visually unresolved companion, the absolute masses and radii of the eclipsing components of the system are determined accurately, and that the system properties are matched by standard evolutionary models. The radii indicate that the components of V 1031 Orionis are near the end of their main-sequence evolution, and these components rotate slower than the synchronous rate observed in similar systems.