Bibcode
Pfeiffer, B.; Vauclair, G.; Dolez, N.; Chevreton, M.; Fremy, J.-R.; Barstow, M. A.; Belmonte, J. A.; Kepler, S. O.; Kanaan, A.; Giovannini, O.; Fontaine, G.; Bergeron, P.; Wesemael, F.; Grauer, A. D.; Nather, R. E.; Winget, D. E.; Provencal, J.; Clemens, J. C.; Bradley, P.; Dixson, J. S.; Kleinman, S. J.; Watson, T. K.; Claver, C. F.; Mazeh, T.; Leibowitz, E. M.; Moskalik, P.
Bibliographical reference
Baltic Astronomy, v.4, p.245-260.
Advertised on:
1995
Citations
4
Refereed citations
4
Description
Fast photometric observations of a cool DAV star, GD 154, obtained with
the Whole Earth Telescope are presented. GD 154 is one of the coolest
pulsating DA white dwarfs and its study is relevant for understanding of
the red edge of the ZZ Ceti instability strip. Its power spectrum is
dominated by three independent modes (P_1=1186.5 s, P_2=1088.6 s and
P_3=402.6 s). It also exhibits harmonics and linear combinations of
these three modes. However, none of the half-integer harmonics, reported
in previous observations, were present during the WET campaign. Assuming
that the observed modes are trapped in the thin outer hydrogen layer, an
identification of the pulsation modes is proposed. The rotation period
(2.3 days) and the mass of the outer hydrogen layer (2 times 10(-10)
M_{*} ) are derived.