2011A&A...532A..50M

The triple stellar system δVel (composed of two A-type and one F-type main-sequence stars) is particularly interesting because it contains one of the nearest and brightest eclipsing binaries. It therefore presents a unique opportunity to determine independently the physical properties of the three components of the system, as well as its distance. We aim at determining the fundamental parameters (masses, radii, luminosities, rotational velocities) of the three components of δVel, as well as the parallax of the system, independently from the existing Hipparcos measurement. We determined dynamical masses from high-precision astrometry of the orbits of Aab-B and Aa-Ab using adaptive optics (VLT/NACO) and optical interferometry (VLTI/AMBER). The main component is an eclipsing binary composed of two early A-type stars in rapid rotation. We modeled the photometric and radial velocity measurements of the eclipsing pair Aa-Ab using a self-consistent method based on physical parameters (mass, radius, luminosity, rotational velocity). From our self-consistent modeling of the primary and secondary components of the δVel A eclipsing pair, we derive their fundamental parameters with a typical accuracy of 1%. We find that they have similar masses, 2.43 ±0.02M_☉ and 2.27±0.02M_☉. The physical parameters of the tertiary component (δVel B) are also estimated, although to a lower accuracy. We obtain a parallax π=39.8±0.4mas for the system, in satisfactory agreement (-1.2σ) with the Hipparcos value (π_Hip=40.5±0.4mas). The physical parameters we derive represent a consistent set of constraints for the evolutionary modeling of this system. The agreement of the parallax we measure with the Hipparcos value to a 1% accuracy is also an interesting confirmation of the true accuracy of these two independent measurements.