The pulsating DA white dwarf star EC 14012-1446: results from four epochs of time-resolved photometry

Abstract

The pulsating DA white dwarfs are the coolest degenerate stars that undergo self-driven oscillations. Understanding their interior structure will help to understand the previous evolution of the star. To this end, we report the analysis of more than 200 h of time-resolved CCD photometry of the pulsating DA white dwarf star EC 14012-1446 acquired during four observing epochs in three different years, including a coordinated three-site campaign. A total of 19 independent frequencies in the star's light variations together with 148 combination signals up to fifth order could be detected. We are unable to obtain the period spacing of the normal modes and therefore a mass estimate of the star, but we infer a fairly short rotation period of 0.61 +/- 0.03 d, assuming the rotationally split modes are l=1. The pulsation modes of the star undergo amplitude and frequency variations, in the sense that modes with higher radial overtone show more pronounced variability and that amplitude changes are always accompanied by frequency variations. Most of the second-order combination frequencies detected have amplitudes that are a function of their parent mode amplitudes, but we found a few cases of possible resonantly excited modes. We point out the complications in the analysis and interpretation of data sets of pulsating white dwarfs that are affected by combination frequencies of the form f_A+f_B-f_C intruding into the frequency range of the independent modes.

arXiv comment14 pages, 6 figures, 6 tables. MNRAS, in press

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Cited by in corpus (8)

• Empirical Determination of Convection Parameters in White Dwarfs I : Whole Earth Telescope Observations of EC14012-1446
• Destroying Aliases from the Ground and Space: Super-Nyquist ZZ Cetis in K2 Long Cadence Data
• Asteroseismology of DAV star EC14012-1446, mode identification and model fittings
• Asteroseismology of DAV star HS0507+0434B, including the core composition profiles
• Asteroseismology of DAV white dwarf stars and G29-38
• The dispersion of period spacing for DAV stars
• Seismic test of the mass-radius relationship of hydrogen-atmospheric white dwarf stars
• Study of Short Period Variables and Small Amplitude Periodic Variables