Modeling the spectrum of TT Hya: an Algol binary with a disc

We calculate the synthetic spectra of TT Hya, an Algol-type eclipsing binary system which contains an A-type primary surrounded by a disc, and an evolved secondary which fills its Roche lobe. A new code SHELLSPEC was developed to solve the simple radiative transfer along the line of sight propagating through the 3D moving medium in LTE. The synthetic spectra are then compared with the observed ones which enable us to derive independent constraints on the behavior of the state quantities, the velocity field and the geometry of the disc.