EDP Sciences
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Volume 443, Number 1, November III 2005
Page(s) 195 - 199
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053362

A&A 443, 195-199 (2005)
DOI: 10.1051/0004-6361:20053362

Two new ZZ Ceti pulsators from the HS and HE surveys

R. Silvotti1, B. Voss2, I. Bruni3, D. Koester2, D. Reimers4, R. Napiwotzki5 and D. Homeier6

1  INAF - Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
    e-mail: silvotti@na.astro.it
2  Institut für Theoretische Physik und Astrophysik der Universität Kiel, Leibnizstraße 15, 24098 Kiel, Germany
    e-mail: voss@astrophysik.uni-kiel.de,koester@astrophysik.uni-kiel.de
3  INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
    e-mail: ivan.bruni@bo.astro.it
4  Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
    e-mail: dreimers@hs.uni-hamburg.de
5  Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
    e-mail: r.napiwotzki@star.herts.ac.uk
6  Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
    e-mail: derek@astro.physik.uni-goettingen.de

(Received 3 May 2005 / Accepted 9 June 2005 )

We report the detection of nonradial g-mode oscillations in the DA white dwarfs HS 1039+4112 (B=15.9) and HE 1429-0343 (B=15.8) from time-series photometry made at the Loiano 1.5 m telescope. The two stars were previously selected as probable pulsators based on two-color photometry and spectral analysis respectively. Following our temperature and surface gravity determinations, HS 1039+4112 ( $\mbox{$T_{\rm eff}$ } = 11\,200$ K, $\mbox{$\log g$ } =8.2$) is located near the red edge of the ZZ Ceti instability strip, whereas HE 1429-0343 ( $\mbox{$T_{\rm eff}$ }=11\,400$ K, $\mbox{$\log g$ }=7.8$) falls in the middle of the strip. Both stars show a multi-mode behavior with the main periods at about 850 and 970 s respectively, and relatively large amplitudes (~7% and ~2.5%).

Key words: stars: white dwarfs -- stars: oscillations -- stars: individual: HS 1039+4112, HE 1429-0343

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© ESO 2005