Multicolor variations of the ZZ Ceti stars

The theoretical color, radial velocity, and line profile variations of a white dwarf undergoing g-mode pulsations are calculated. It is found that the luminosity and color variations of the white dwarf are caused by its temperature variations, not by its geometry or gravity variations. It is also found that the variations in the profiles and radial velocities of the absorption lines in the spectrum of the white dwarf will be too small to be measured. This lack of variation in the line profiles and velocities should unambiguously distinguish the g-mode pulsations from the r-mode pulsations. Results of multicolor photometry of the ZZ Ceti star R548 are also reported. It is found that, to within the observational errors, the luminosity variations of R548 are consistent with temperature variations. Thus, it is concluded that the properties of the pulsations of R548 are consistent with the expected properties of g-mode pulsations.

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