1998A&A...329L..13G

We report the discovery of a new long-period ZZ Ceti star through the analysis of photometric time series gathered on 7 nights between 1995 and 1996. The light curve displays a periodic variation with a period of ∼18min in white light and the frequency analysis reveals a low frequency peak at ∼0.92mHz with an amplitude varying from 0.007 to 0.025mag present every night. BPM 24754 is the 28th known ZZ Ceti star and it has the second longest period. We have also determined its atmospheric parameters using line profile fitting and its mass using white dwarf evolutionary models. BPM 24754 has T_eff=12,900±320K, logg=8.04±0.08, and M=0.63±0.04M_☉. We compare its T_eff in relation to the ZZ Ceti instability strip.