The pulsation modes of the pre-white dwarf PG 1159-035
Abstract
PG 1159-035, a pre-white dwarf with T_eff=140,000 K, is the prototype of both two classes: the PG1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. In this work, we used all available WET photometric data from 1983, 1985, 1989, 1993 and 2002 to identify the pulsation periods and identified 76 additional pulsation modes, increasing to 198 the number of known pulsation modes in PG 1159-035, the largest number of modes detected in any star besides the Sun. From the period spacing we estimated a mass M = 0.59 +/- 0.02 solar masses for PG 1159-035, with the uncertainty dominated by the models, not the observation. Deviations in the regular period spacing suggest that some of the pulsation modes are trapped, even though the star is a pre-white dwarf and the gravitational settling is ongoing. The position of the transition zone that causes the mode trapping was calculated at r_c = 0.83 +/- 0.05 stellar radius. From the multiplet splitting, we calculated the rotational period P_rot = 1.3920 +/- 0.0008 days and an upper limit for the magnetic field, B < 2000 G. The total power of the pulsation modes at the stellar surface changed less than 30% for l=1 modes and less than 50% for l=2 modes. We find no evidence of linear combinations between the 198 pulsation mode frequencies. PG 1159-035 models have not significative convection zones, supporting the hypothesis that nonlinearity arises in the convection zones in cooler pulsating white dwarf stars.
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Cite
@article{arxiv.0711.2244,
title = {The pulsation modes of the pre-white dwarf PG 1159-035},
author = {J. E. S. Costa and S. O. Kepler and D. E. Winget and M. S. O'Brien and S. D. Kawaler and A. F. M. Costa and O. Giovannini and A. Kanaan and A. S. Mukadam and F. Mullally and A. Nitta and J. L. Provençal and H. Shipman and M. A. Wood and T. J. Ahrens and A. Grauer and M. Kilic and P. A. Bradley and K. Sekiguchi and R. Crowe and X. J. Jiang and D. Sullivan and T. Sullivan and R. Rosen and J. C. Clemens and R. Janulis and D. O'Donoghue and W. Ogloza and A. Baran and R. Silvotti and S. Marinoni and G. Vauclair and N. Dolez and M. Chevreton and S. Dreizler and S. Schuh and J. Deetjen and T. Nagel and J. -E. Solheim and J. M. Gonzalez Perez and A. Ulla and Martin Barstow and M. Burleigh and S. Good and T. S. Metcalfe and S. -L. Kim and H. Lee and A. Sergeev and M. C. Akan and Ö. Çakirli and M. Paparo and G. Viraghalmy and B. N. Ashoka and G. Handler and Özlem Hürkal and F. Johannessen and S. J. Kleinman and R. Kalytis and J. Krzesinski and E. Klumpe and J. Larrison and T. Lawrence and E. Meištas and P. Martinez and R. E. Nather and J. -N. Fu and E. Pakštienė and R. Rosen and E. Romero-Colmenero and R. Riddle and S. Seetha and N. M. Silvestri and M. Vučković and B. Warner and S. Zola and L. G. Althaus and A. H. Córsico and M. H. Montgomery},
journal= {arXiv preprint arXiv:0711.2244},
year = {2007}
}
Comments
25 pages, 11 figures, appendix with 6 long tables. The resolution of some of the figures were changed and some of them can appear with a bit lower quality