VLTI near-IR interferometric observations of Vega-like stars

Abstract

We report in this paper the direct interferometric measurement of the angular diameter of five nearby Vega-like stars: PsA, Leo, Pic, Eri and 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 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.