A Search for Pulsation in Twenty-One White Dwarfs

Abstract

Well-defined astrophysical constraints of white dwarfs (WDs), such as on the presence or absence of pulsational variability, are very much needed to refine and develop current models. Because these stars are rather faint and variability periods are mostly below one hour, only a very limited amount of space-based data is currently available for these objects. We present about 68 hours of highquality ground-based photometric time-series data for twenty-one WDs acquired at five different observatories. No new pulsators were detected but the derived upper limits of variability, which are typically on the order of only a few mmags, provide important input for pulsation models.