A STUDY OF THE INFRARED-SPECTRUM OF PSI-PERSEI .1. A PARAMETER STUDY OF THE DISC MODEL

We report a parameter study of emission lines arising from a disc surr ounding a Be star, using parameters appropriate to the Be star psi Per . We concentrate on the Hn line and on some IR recombination lines (Br alpha, Br gamma, Pf gamma, and HI 17-6). The model we use is a simple cone-like disc model, first proposed by Waters (1986). This model has been successful in explaining the continuum energy distribution of Be stars, and we now wish to study the emission line spectrum emerging f rom such a disc. We find that line shapes and ratios of line strengths are strongly dependent on the temperature structure of the disc. Infr ared recombination lines will therefore be very useful in determining the physical state of the circumstellar envelopes of Be stars.