VLTI near-IR interferometric observations of Vega-like stars

Radius and age of α PsA, β Leo, β Pic, ϵ Eri and τ Cet

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: α PsA, β Leo, β Pic, ϵ Eri and τ 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 β 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 [CITE]) 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.