The light curve of the ZZ ceti star G226-29

Abstract

G226-29 is a pulsating DA white dwarf, or ZZ Ceti star. Using 65 hr of high-speed photometry accumulated from 1980 to 1982, we have decomposed the light curve of G226-29 into its component pulsations. There are three pulsations in the light curve, ali of which have periods dose to 109.3 s. Their fractional semiamplitudes and periods are 0.0031 and 109.08684 s, 0.0011 and 109.27929 s, and 0.0031 and 109.47242 s. The pulsations are evenly spaced in frequency, and those with the longest and shortest periods have nearly equal amplitudes. We propose that the pulsations are g-mode pulsations with the same values of I and k, but with different values of m, whose periods have been split by slow rotation of the white dwarf. Depending on the specific value of I we assign to the pulsations, the equatorial rotational velocity of G226-29 is between I and 2 km s-ˡ.