Pulsational instability domain of Delta Scuti variables

An updated theoretical instability domain of the Delta Scuti star models in the Hertzsprung-Russell diagram, in the log g - log Teff diagram and in diagrams for dereddened uvby-beta photometric indices is presented. The sensitivity of both the position of the evolutionary tracks and the Blue Edge of the instability domain to changes in the chemical composition parameters (X, Z) and to changes in the convection theory parameters (mixing-length in the stellar envelope, the extent of the overshooting from the convective core) is discussed.