BPM-24754 - A NEW SOUTHERN ZZ-CETI STAR

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 similar to 18 min in white light and the frequency analysis reveals a low frequency peak at similar to 0.92 mHz with an amplitude varying from 0.007 to 0.025 mag present every night. BPM 24754 is the 28th kn own ZZ Ceti star and it has the second longest period. We have also de termined its atmospheric parameters using line profile fitting and its mass using white dwarf evolutionary models. BPM 24754 has T-eff = 12, 900 +/- 320 K, log g = 8.04 +/- 0.08, and M = 0.63 +/- 0.04 M.. We com pare its T-eff in relation to the ZZ Ceti instability strip.