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Issue A&A
Volume 426, Number 2, November I 2004
Page(s) 601 - 617
Section Stellar structure and evolution
DOI 10.1051/0004-6361:20047189



A&A 426, 601-617 (2004)
DOI: 10.1051/0004-6361:20047189

VLTI near-IR interferometric observations of Vega-like stars

Radius and age of $\alpha$ PsA, $\beta$ Leo, $\beta$ Pic, $\epsilon$ Eri and $\tau$ Cet
E. Di Folco1, F. Thévenin2, P. Kervella3, 4, A. Domiciano de Souza5, 6, V. Coudé du Foresto4, D. Ségransan7 and P. Morel2

1  European Southern Observatory, Karl-Schwarzschild Straße 2, 85748 Garching, Germany
    e-mail: edifolco@eso.org
2  Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
3  European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19, Chile
4  Laboratoire d'Études Spatiales et d'Instrumentation Astrophysique, Observatoire de Paris, Meudon, France
5  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
6  Laboratoire Universitaire d'Astrophysique de Nice - UNSA, CNRS UMR 6525, Parc Valrose, Nice, France
7  Observatoire de Genève, 51 chemin des maillettes, 1290 Sauverny, Switzerland

(Received 3 February 2004 / Accepted 11 May 2004 )

Abstract
We report in this paper the direct interferometric measurement of the angular diameter of five nearby Vega-like stars: $\alpha$ PsA, $\beta$ Leo, $\beta$ Pic, $\epsilon$ Eri and $\tau$ Cet. The near-infrared ( K and H bands) observations were conducted at the VLTI during the commissioning period with the VINCI instrument and three different baselines ranging from 66 m to 140 m. The five stellar photospheres are resolved and we derive their angular diameters with a 1 to 2% accuracy, except for $\beta$ Pic (14%). We discuss the detectability and the influence of a possible small amount of warm circumstellar dust on our measurements. In addition, we have used the stellar evolution code CESAM (Morel 1997) to compare the computed fundamental parameters to the observed values (linear diameter, luminosity, temperature and chemical abundance). As a result of the simulation, the age of the stars is inferred and found to be in good agreement with previous estimates from various other methods.


Key words: techniques: interferometric -- infrared: stars -- stars: fundamental parameters -- stars: circumstellar matter -- stars: general

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