Multicolor Photometry for Mode Identification

Abstract

The goal of asteroseismology is to discern the physical conditions of stars by comparing observed pulsations with models.To obtain this goal, the observed pulsation periods and the spherical harmonics (n, ℓ, and m) need to match the theoretical model.Typically the most difficult part in this process is the identification of the pulsation modes in the observations.Multicolour photometry is one method that has proven useful for identifying pulsation modes.By observing stars through various wavebands, and comparing the amplitudes and phases, it is possible to determine the spherical harmonics.This contribution will emphasize the work of Watson (1988), which has since been applied to many different types of variable stars including δ Scuti (Garrido et al., 1990), γ Doradus (Breger et al., 1997), β Cepheid (Cugier et al., 1994), and EC 14026 (Koen, 1998) stars. I will also discuss the technique of summing spectra (especially UV) into various wavebands which are then used to identify modes as pioneered by Robinson, Kepler, and Nather (1982) and applied to white dwarf stars (Kepler et al., 2000).