The Delta Scuti Star GX Pegasi: A Theoretical Investigation of its Power Spectrum

Target of a STEPHI multisite campaign, the Delta Scuti star GX Pegasi has been found to oscillate with at least five simultaneous, close frequencies (table I).Mode identification together with informations about the star that such an identification can provide are outlined below (see also Michel et al, 1992b).The mode identification is carried out by means of a comparison between the observed frequencies and the adiabatic frequencies of models appropriate to this star. Models that match GX Peg’s position in a Hertzsprung-Russell diagram have masses in the range 1.9 – M⊙. When included, convective core overshoot is handled as in Maeder and Meynet (1989). According to these models, GX Peg is a rather evolved, main sequence star.