Volume 532, August 2011
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||21 July 2011|
The nearby eclipsing stellar system δ Velorum
III. Self-consistent fundamental parameters and distance⋆
European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19, Chile
2 LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
3 Astronomical Institute Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic
4 Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergäßchen 2-3, 07745 Jena, Germany
5 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
6 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
7 Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze, Italy
8 School of Cosmic Physics, Dublin Institute for Advanced Studies, Dublin 2, Republic of Ireland
9 UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble 38041, France
10 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
11 Laboratoire Fizeau, Université de Nice, CNRS-Observatoire de la Côte d’Azur, 06108 Nice Cedex 2, France
Received: 15 March 2011
Accepted: 7 June 2011
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 (πHip = 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.
Key words: binaries: eclipsing / stars: early-type / stars: rotation / stars: individual:δVelorum (HD 74956) / techniques: high angular resolution / techniques: interferometric
© ESO, 2011
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