EDP Sciences
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Volume 488, Number 3, September IV 2008
Page(s) L67 - L70
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200810624
Published online 08 August 2008

A&A 488, L67-L70 (2008)
DOI: 10.1051/0004-6361:200810624


$\delta$ Centauri: a new binary Be star detected by VLTI/AMBER spectro-interferometry

A. Meilland1, F. Millour1, Ph. Stee2, A. Spang2, R. Petrov2, D. Bonneau2, K. Perraut3, and F. Massi4

1  Max Planck Intitut fur Radioastronomie, Auf dem Hugel 69, 53121 Bonn, Germany
    e-mail: meilland@mpifr-bonn.mpg.de
2  Laboratoire A.H. FIZEAU, UMR 6525, UNS/OCA/CNRS, Campus Valrose, 06108 Nice Cedex 2, France
3  Laboratoire d'Astrophysique de Grenoble, UMR 5571 Université Joseph Fourier/CNRS, BP 53, 38041 Grenoble Cedex 9, France
4  INAF – Osservatorio Astrofisico di Arcetri, Istituto Nazionale di Astrofisica, Largo E. Fermi 5, 50125 Firenze, Italy

Received 16 July 2008 / Accepted 29 July 2008

Aims. We study the Be star $\delta$ Cen circumstellar disk using long-baseline interferometry which is the only observing technique capable of resolving spatially and spectroscopically objects smaller than 5 mas in the H and K band.
Methods. We used the VLTI/AMBER instrument on January 6, 8, and 9, 2008, in the H and K bands to complete low (35) and medium (1500) spectral resolution observations.
Results. We detected an oscillation in the visibility curve plotted as a function of the spatial frequency which is a clear signature of a companion around $\delta$ Cen. Our best-fit soltution infers a binary separation of 68.7 mas, a companion flux contribution in the K band of about 7% of the total flux, a PA of 117.5$\degr$, and an envelope flux around the Be primary that contributes up to about 50% of the total flux, in agreement with our Spectral Energy Distribution (SED) fit. The envelope size is estimated to be 1.6 mas in K but no departure from spherical symmetry is detected.

Key words: techniques: high angular resolution -- techniques: interferometric -- stars: emission-line, Be -- stars: binaries: close -- stars: winds, outflows -- 
stars: circumstellar matter

© ESO 2008