A description of the shellspec code

Program shellspec is designed to solve simple radiative transfer along the line of sight in moving media. The scattered light from a central object can be taken into account assuming an optically thin environment. Output intensities are then integrated through the 2D projection surface of a 3D object. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, shell or stars as well as an empty space may be defined (embedded) in 3D and their composite synthetic spectrum calculated. The stars may have the Roche geometry and known intrinsic spectra. Synthetic light curves or trailing spectrograms can be produced by changing your view points on the 3D object.

An application to the accretion disc system of TT Hya type (Algol-type eclipsing binary with a disc) is included and the influence of various effects on the emerging spectrum is studied.