We model the L1551 IRS5 source as a system containing two protostars, each surrounded by a circumstellar disk, both encircled by a circumbinary disk, and all disks surrounded by an extended infalling flattened envelope With this composite model, we can calculate self-consistently the spectral energy distribution of the source the shape of the ice and silicate features, and the spatial intensity distributions of the envelope and disks. We compare our model results with the observations, determining the physical parameters of the disks and the envelope. We find that flattened envelope collapse models are required in order to explain the observations and that the infall rate of the envelope is much larger than the accretion rates of the binary disks.

The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL on 2003, January 29. We carried out optical and near-infrared (NIR) observations at the European Southern Observatory (ESO La Silla) in the course of a Target of Opportunity (ToO) programme. We discovered the optical counterpart and confirmed an already proposed NIR candidate. NIR spectroscopy revealed a large amount of emission lines, including forbidden iron lines and P-Cygni profiles. The spectral energy distribution of the source points towards a high luminosity and a high temperature, with an absorption greater than the interstellar absorption, but two orders of magnitude lower than the X-ray absorption. We show that the source is an High Mass X-ray binary (HMXB) at a distance between ~ 1 and ~ 6 kpc, the mass donor being an early-type star, probably a sgB[e] star, surrounded by a rich and absorbing circumstellar material. This would make the second High Mass X-ray Binary (HMXB) with a sgB[e] star after CI Cam, indicating that a new class of strongly absorbed X-ray binaries is being unveiled by INTEGRAL.