delta Cen: a new binary Be star detected by VLTI/AMBER spectro-interferometry

TL;DR

This study used VLTI/AMBER interferometry to discover and characterize a binary companion around the Be star delta Cen, revealing details about its separation, flux contribution, and circumstellar environment.

Contribution

First detection of a binary companion around delta Cen using spectro-interferometry, providing detailed measurements of the system's separation, flux ratio, and circumstellar envelope.

Findings

Binary separation of 68.7 mas

Companion flux contribution of ~7% in K band

Envelope contributes up to 50% of total flux

Abstract

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 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 $\delta$ 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.