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.

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

References in corpus (2)

• New nonadiabatic pulsation computations on full PG1159 evolutionary models: the theoretical GW Vir instability strip revisited
• High-resolution ultraviolet spectroscopy of PG1159-035 with HST and FUSE

Cited by in corpus (15)

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• Asteroseismological measurements on PG 1159-035, the prototype of the GW Vir variable stars
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• Precision asteroseismology of the pulsating white dwarf GD 1212 using a two-wheel-controlled Kepler spacecraft
• The temporal changes of the pulsational periods of the pre-white dwarf PG 1159-035
• Evidence of thin helium envelopes in PG1159 stars
• Revealing the pulsational properties of the V777 Her star KUV 05134+2605 by its long-term monitoring
• On Trapped Modes In Variable White Dwarfs As Probes Of The ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O Reaction Rate
• On the possible existence of short-period g-mode instabilities powered by nuclear burning shells in post-AGB H-deficient (PG1159-type) stars
• Discovery of a new PG1159 (GW Vir) Pulsator
• On the systematics of asteroseismological mass determinations of PG1159 stars
• Shear viscosity of degenerate electron matter
• Kepler and TESS Observations of PG 1159-035
• Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS VI. Asteroseismology of the GW Vir-type central star of the Planetary Nebula NGC 246
• Asteroseismology of the DOV star PG 1159-035