Evolution of mode periods in the inertial frame versus equatorial rotation velocity. The observed periods of HD 261810 are shown with horizontal red lines. The stable modes are shown with gray dots, while the excited modes are shown with blue dots. Left: the dipole prograde modes provide a possible period match for v_rot = 235 km s^-1. Right: the quadrupole zonal modes can equally provide a fit for v_rot = 270 km s^-1. Table 14 summarizes the results for different ℓ and m.