Period and Amplitude Changes in the GW Vir Variable Star PG 0122+200: Evidence for Resonant Coupling

Based on 22 years of observations, we obtained the frequency and amplitude variations of the 7 largest amplitude modes of the GW Vir star PG 0122+200. We find that these variations occur on a much shorter time scale and with larger amplitude than predicted by theoretical evolutionary models in which the frequency variations only result from the star cooling. This suggests that the observed variations are due to the resonant mode coupling induced by rotation within the triplets.