Abell 43, a second pulsating “hybrid-PG 1159” star

We report observations of the planetary nebula nucleus Abell 43, obtained at the 2.5 m Nordic Optical Telescope, which show that it is a pulsator. Abell 43, a “hybrid-PG 1159” type star, is the second pulsator of this class, after HS 2324+3944. From the limited data set acquired, we find that Abell ...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2005-04, Vol.433 (3), p.1097-1100
Main Authors: Vauclair, G., Solheim, J.-E., Østensen, R. H.
Format: Article
Language:English
Subjects:
ISM: planetary nebulae: individual: Abell 43
stars: individual: hybrid-PG 1159
stars: oscillations
stars: white dwarfs
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Summary:We report observations of the planetary nebula nucleus Abell 43, obtained at the 2.5 m Nordic Optical Telescope, which show that it is a pulsator. Abell 43, a “hybrid-PG 1159” type star, is the second pulsator of this class, after HS 2324+3944. From the limited data set acquired, we find that Abell 43 exhibits at least two periods of 2600 s and 3035 s, the longest ones observed up to now in PG 1159 and “hybrid-PG 1159” pulsators. This strongly suggests that the variations are due to non-radial g-mode pulsations and cannot be a consequence of binarity. This discovery raises puzzling questions regarding the excitation mechanism in this H rich, C and O poor “hybrid-PG 1159” since the C and O abundances are too low to trigger the instability through the κ-mechanism induced by the partial ionization of C and O, a mechanism invoked to explain the instability in the PG 1159 stars and in the previously known “hybrid-PG 1159” pulsator HS 2324+3944.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361:20041999