The interferometric diameter and internal structure of Sirius A

P. Kervella; F. Thévenin; P. Morel; P. Bordé; E. Di Folco

doi:doi:10.1051/0004-6361:20030994

Free access

Issue		A&A Volume 408, Number 2, September III 2003


Page(s)		681 - 688
Section		Stellar atmospheres
DOI		http://dx.doi.org/10.1051/0004-6361:20030994

A&A 408, 681-688 (2003)
DOI: 10.1051/0004-6361:20030994

The interferometric diameter and internal structure of Sirius A

P. Kervella¹, F. Thévenin², P. Morel², P. Bordé³ and E. Di Folco⁴

¹ European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19, Chile
² Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
³ LESIA, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France
⁴ European Southern Observatory, Karl-Schwarzschild-str. 2, 85748 Garching, Germany

(Received 10 April 2003 / Accepted 23 June 2003)

Abstract
The interferometric observations of dwarf stars in the solar neighbourhood, combined with HIPPARCOS parallaxes provide very precise values of their linear diameters. In this paper, we report the direct measurement of the angular diameter of the bright star Sirius A with the VINCI/VLTI instrument. We obtain a uniform disk angular diameter of $\theta_{\rm UD} = 5.936 \pm 0.016$ mas in the K band and a limb darkened value of $\theta_{\rm LD} = 6.039 \pm 0.019$ mas. In combination with the HIPPARCOS parallax of $379.22 \pm 1.58$ mas, this translates into a linear diameter of $1.711 \pm 0.013~D_{\odot}$ . Using the VINCI/VLTI interferometric diameter and the published properties of Sirius A, we derive internal structure models corresponding to ages between 200 and $250 \pm 12$ Myr. This range is defined mainly by the hypothesis on the mass of the star, the overshoot and the metallicity.

Key words: stars: individual: Sirius -- stars: fundamental parameters -- stars: evolution -- techniques: interferometric

Offprint request: P. Kervella, pkervell@eso.org

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