We study the Be star δ 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 b and. 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 (150 0) spectral resolution observations. We detected an oscillation in the visibility curve plotted as a function of the spatial frequency which is a clear signat ure of a companion around δ Cen. Our best-fit soltution infers a binary separation of 68.7 mas, a companion flux co ntribution 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 e nvelope size is estimated to be 1.6 mas in K but no departure from spherical symmetry is detected.
@article{arxiv.0807.4622,
title = {delta Cen: a new binary Be star detected by VLTI/AMBER spectro-interferometry},
author = {Anthony Meilland and Florentin Millour and Philippe Stee and Alain Spang and R. G. Petrov and D. Bonneau and Karine Perraut and Fabrizio Massi},
journal= {arXiv preprint arXiv:0807.4622},
year = {2009}
}