Poster abstract details

Surface layer corrections in asteroseismic model fitting
ian W Roxburgh


We show that the frequency offset for the Sun is better modelled by a polynomial rather than a simple power law and argue that the offset should be treated as an unknown and determined as part of the model fitting procedure when comparing an observed frequency set with that of models. By comparing models with and without a frequency dependent addition to a frequency set it is shown that the internal phase-shifts, and hence internal structure of the two models are different. Hence, in principle, the internal structure of a best fit model to an observed frequency set that has had a surface correction added is not that of the observed star. The error is small being of the order of the percentage change in the frequencies on adding the surface correction but can be significant in evolved stars.