Pulsation in the white dwarf HE 1017–1352: confirmation of the class of hot DAV stars

Abstract

We report the detection of periodic variations on the Teff ≃ 32 000 K DA white dwarf star HE 1017–1352. We obtained time series photometry using the 4.1-m SOAR telescope on three separate nights for a total of 16.8 h. From the frequency analysis we found four periods of 605 s, 556 s, 508 s and 869 s with significant amplitudes above the 1/1000 false alarm probability detection limit. The detected modes are compatible with low harmonic degree g-mode non-radial pulsations with radial order higher than ∼9. This detection confirms the pulsation nature of HE 1017–1352 and thus the existence of the new pulsating class of hot DA white dwarf stars. In addition, we detect a long period of 1.52 h, compatible with a rotation period of DA white dwarf stars.