Limits Of Perturbative Nonlinear Light Curve Analyses: The Case Of G117-B15A

This poster examines the nonlinear combination frequencies found in the DAV G117-B15A. Using multiple epochs of observations we show that the ratio of the amplitude of the combination frequencies to those of the parent frequencies is not constant in time but rather varies on a time scale of years. This variation is difficult to explain in any model in which the modeled nonlinearities are second order, such as that of Brassard et al. [2], which accounts for these nonlinearities via the conversion from temperature variations to flux variations. In contrast, due to its extreme sensitivity, the convective light curve model can accomodate these variations with only modest variations in parameters such as T(eff).