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Astron. Astrophys. 339, 170-172 (1998)

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Research Note

A search for pulsations among low-mass DAO white dwarfs

G. Handler *

Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, A-1180 Wien, Austria

Received 29 June 1998 / Accepted 27 July 1998


We performed a search for periodic light variations among low-mass DAO white dwarfs. These objects have theoretically been predicted to exhibit low-order g-mode pulsations due to a potent [FORMULA] mechanism in hydrogen-burning shells according to model calculations of Charpinet et al. (1997).

No pulsations were detected in any of our nine candidate stars. This can be attributed to the very narrow instability strip predicted or to the fact that pulsationally unstable modes are not necessarily excited, a common phenomenon among pulsating stars. It may also be the case that hydrogen-burning shells in the stars are too small to drive pulsations or not present.

Key words: white dwarfs – stars: oscillations

* Visiting Astronomer, The University of Texas and McDonald Observatory

Send offprint requests to: gerald@dsn.astro.univie.ac.at

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© European Southern Observatory (ESO) 1998

Online publication: September 30, 1998