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Astron. Astrophys. 329, L13-L16 (1998)

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Letter to the Editor

BPM 24754: A new Southern ZZ Ceti star *

O. Giovannini 1, S.O. Kepler 1, A. Kanaan 1, A.F.M. Costa 1 and D. Koester 2

1 Instituto de Fsica, Universidade Federal do Rio Grande do Sul, CEP 91501-970, Porto Alegre - RS, Brazil
2 Institut für Astronomie und Astrophysik, Universität Kiel, D-24098 Kiel, Germany

Received 21 August 1997 / Accepted 25 September 1997


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 [FORMULA] 18 min in white light and the frequency analysis reveals a low frequency peak at [FORMULA] 0.92 mHz with an amplitude varying from 0.007 to 0.025 mag 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 [FORMULA]  K, [FORMULA], and [FORMULA]. We compare its [FORMULA] in relation to the ZZ Ceti instability strip.

Key words: stars: individual: BPM 24754 – stars: variables: other – stars: oscillations – stars: fundamental parameters – white dwarfs

* Based on observations obtained at the Laboratório Nacional de Astrofsica/CNPq, Brazil, and at the Cerro Tololo Inter-American Observatory. CTIO is operated by AURA, Inc. under contract to the National Science Foundation.

Present address: Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901-6988, USA. E-mail: odilon@kepler.pss.fit.edu

Send offprint requests to: O. Giovannini

© European Southern Observatory (ESO) 1998

Online publication: November 24, 1997