Mass and Δν for different isochrone models are shown in the figure along with the observed Δν and mass of four stars N77-210, N77-255, N77-325, and N77-342, which are marked as ellipses. The Δν of pulsation models corresponding to different theoretical masses are shown (black filled circles). The height and width of the ellipses represent the error in the Δν measurements and the mass ranges.