We present optical WBVR and infrared JHKL photometric observations of the Be binary system \delta  Sco , obtained in 2000–2005 , mid-infrared ( 10 and 18 \mu m ) photometry and optical ( \lambda \lambda 3200–10500 à ) spectropolarimetry obtained in 2001 .
Our optical photometry confirms the results of much more frequent visual monitoring of \delta  Sco .
In 2005 , we detected a significant decrease in the object ’ s brightness , both in optical and near-infrared brightness , which is associated with a continuous rise in the hydrogen line strenghts .
We discuss possible causes for this phenomenon , which is difficult to explain in view of current models of Be star disks .
The 2001 spectral energy distribution and polarization are succesfully modeled with a three-dimensional non-LTE Monte Carlo code which produces a self-consistent determination of the hydrogen level populations , electron temperature , and gas density for hot star disks .
Our disk model is hydrostatically supported in the vertical direction and radially controlled by viscosity .
Such a disk model has , essentially , only two free parameters , viz. , the equatorial mass loss rate and the disk outer radius .
We find that the primary companion is surrounded by a small ( 7 R _ { \star } ) , geometrically-thin disk , which is highly non-isothermal and fully ionized .
Our model requires an average equatorial mass loss rate of 1.5 \times 10 ^ { -9 } M _ { \sun } yr ^ { -1 } .