The nearby eclipsing stellar systemδVelorum

Abstract

Context. The triple stellar system δ Vel (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. Aims. We aim at determining the fundamental parameters (masses, radii, luminosities, rotational velocities) of the three components of δ Vel, as well as the parallax of the system, independently from the existing Hipparcos measurement. Methods. 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). Results. From our self-consistent modeling of the primary and secondary components of the δ Vel A eclipsing pair, we derive their fundamental parameters with a typical accuracy of 1%. We find that they have similar masses, 2.43 ± 0.02 M and 2.27 ± 0.02 M . The physical parameters of the tertiary component (δ Vel B) are also estimated, although to a lower accuracy. We obtain a parallax π = 39.8 ± 0.4 mas for the system, in satisfactory agreement (−1.2 σ) with the Hipparcos value (π Hip = 40.5 ± 0.4 mas). Conclusions. 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.

Interferometry, spectroscopy and high precision astrometry of δ Velorum

“…Mérand et al ( [10]) collected interferometric observations of the δ Vel Aab system using the AMBER instrument of the VLTI. This new observable allowed to retrieve the visual orbit of the eclipsing pair ( Fig.…”

“…This progression allowed a relatively regular monitoring of the visual orbit of the pair, down to the sub-arcsecond separations that occur around the periastron passage. Thanks to the large aperture of the UT4 telescope of the VLT and the diffraction-limited angular resolution ( [10]), the NACO observations provide high-precision relative astrometry of the A-B pair. In addition to these recent astrometric measurements, we also took advantage of the historical astrometric positions assembled by Argyle et al ([11]), that include 17 epochs between 1895 and 1999.…”

“…5. The detailed orbital elements are listed in [10]. Using the parallax determined from the eclipsing pair observations described in Sect.…”

“…Visual orbit of the eclipsing binary δ Vel Aab as measured by interferometry with VLTI/AMBER (taken from[10])…”

“…Astrometry and adjusted orbit of δ Vel AB, from[10] (the relevant references are given therein).around the individual eclipsing components Aa or Ab (although the stability of such planetary systems may be problematic) or around the Aab pair.…”