The asteroseismological potential of the pulsating DB white dwarf stars CBS 114 and PG 1456+103

Handler, G.; Metcalfe, T. S.; Wood, M. A.

doi:10.1046/j.1365-8711.2002.05655.x

Cited by 19 publications

(21 citation statements)

References 28 publications

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“…Although there are slight differences between the profile from our parametrization compared with that of Fontaine & Brassard (2002), we have verified that modifications to the detailed shape of the profile comparable to these differences lead to only marginal improvements in the final fits. Note that the two layers are theoretically expected to merge into one at low values of T eff (Gautschy & Althaus 2002), leading to structures that have effectively been explored by the single‐layered global model fitting of Metcalfe et al (2001) and Handler, Metcalfe & Wood (2002) for GD 358 and CBS 114 respectively.…”

Section: Theoretical Modelsmentioning

confidence: 99%

Probing the core and envelope structure of DBV white dwarfs

Metcalfe

Montgomery

Kawaler

2003

Monthly Notices RAS

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We investigate the global pulsation properties of DBV white dwarf models that include both the double-layered envelope structure expected from time-dependent diffusion calculations, as well as a non-uniform C/O core expected from prior nuclear burning. We compare these models to otherwise identical models containing a pure C core to determine whether the addition of core structure leads to any significant improvement. Our double-layered envelope model fit to GD 358 that includes an adjustable C/O core is significantly better than our pure C core fit (7sigma improvement). We find a comparable improvement from fits to a second DBV star, CBS 114, though the values of the derived parameters may be more difficult to reconcile with stellar evolution theory. We find that our models are systematically cooler by 1,900 K relative to the similar models of Fontaine & Brassard (2002). Although a fit to their model reproduces the mass and envelope structure almost exactly, we are unable to reproduce the absolute quality of their fit to GD 358. Differences between the constitutive physics employed by the two models may account for both the temperature offset and the period residuals.Comment: 5 pages, minor changes, to be published in MNRAS Letter

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Section: Theoretical Modelsmentioning

confidence: 99%

Probing the core and envelope structure of DBV white dwarfs

Metcalfe

Montgomery

Kawaler

2003

Monthly Notices RAS

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“…Although the mode amplitudes of GD 358 vary, the associated pulsation frequencies seem reasonably stable (Kepler et al 2003). Very recently, some amplitude and frequency variations have also been reported for the DBVs CBS 114 and PG 1456+103 (Handler, Metcalfe & Wood 2002).…”

Section: Introductionmentioning

confidence: 90%

Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

Handler¹,

O’Donoghue²,

Müller³

et al. 2003

Monthly Notices of the Royal Astronomical Society

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We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single‐site photometry is also presented. We use all these data plus all available archival measurements to study the temporal behaviour of the pulsational amplitudes and frequencies of these stars for the first time. We demonstrate that both KUV 05134+2605 and PG 1654+160 pulsate in many modes, the amplitudes of which are variable in time; some frequency variability of PG 1654+160 is also indicated. Beating of multiple pulsation modes cannot explain our observations; the amplitude variability must therefore be intrinsic. We cannot find stable modes to be used for determinations of the evolutionary period changes of the stars. Some of the modes of PG 1654+160 appear at the same periods whenever detected. The mean spacing of these periods (≈40 s) suggests that they are probably caused by non‐radial gravity‐mode pulsations of spherical degree ℓ= 1. If so, PG 1654+160 has a mass around 0.6 M⊙. The time‐scales of the amplitude variability of both stars (down to two weeks) are consistent with theoretical predictions of resonant mode coupling, a conclusion which might however be affected by the temporal distribution of our data.

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“…Handler et al 2003 and2002). The most famous example is the so-called sforzando effect observed in GD 358.…”

Section: Introductionmentioning

confidence: 99%

Revealing the pulsational properties of the V777 Herculis star KUV 05134+2605 by its long-term monitoring

Bognár

Paparó

Córsico

et al. 2014

A&A

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Context. KUV 05134+2605 is one of the 21 pulsating DB white dwarfs (V777 Her or DBV variables) known so far. The detailed investigation of the short-period and low-amplitude pulsations of these relatively faint targets requires considerable observational efforts from the ground, long-term single-site or multi-site observations. The observed amplitudes of excited modes undergo short-term variations in many cases, which makes determining pulsation modes difficult. Aims. We aim to determine the pulsation frequencies of KUV 05134+2605, find regularities between the frequency and period components, and perform an asteroseismic investigation for the first time. Methods. We re-analysed the published data and collected new measurements. We compared the frequency content of the different datasets from the different epochs and performed various tests to check the reliability of the frequency determinations. The mean period spacings were investigated with linear fits to the observed periods, Kolmogorov-Smirnov and inverse variance significance tests, and with a Fourier analysis of different period sets, including a Monte Carlo test that simulated the effect of alias ambiguities. We employed fully evolutionary DB white dwarf models for the asteroseismic investigations. Results. We identified 22 frequencies between 1280 and 2530 μHz. These form 12 groups, which suggests at least 12 possible frequencies for the asteroseismic investigations. Thanks to the extended observations, KUV 05134+2605 joined the group of rich white dwarf pulsators. We identified one triplet and at least one doublet with a ≈9 μHz frequency separation, from which we derived a stellar rotation period of 0.6 d. We determined the mean period spacings of ≈31 s and 18 s for the modes we propose as dipole and quadrupole. We found an excellent agreement between the stellar mass derived from the = 1 period spacing and the period-to-period fits, all providing M * = 0.84−0.85 M solutions. Our study suggests that KUV 05134+2605 is the most massive amongst the known V777 Her stars.

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The asteroseismological potential of the pulsating DB white dwarf stars CBS 114 and PG 1456+103

Cited by 19 publications

References 28 publications

Probing the core and envelope structure of DBV white dwarfs

Probing the core and envelope structure of DBV white dwarfs

Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

Revealing the pulsational properties of the V777 Herculis star KUV 05134+2605 by its long-term monitoring

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