The pulsating DA white dwarf star EC 14012−1446: results from four epochs of time-resolved photometry |
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| Authors: | G Handler E Romero-Colmenero J L Provencal K Sanchawala M A Wood I Silver W-P Chen |
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| Institution: | Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, A-1180 Wien, Austria;South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;Mt Cuba Observatory &Department of Physics and Astronomy, University of Delaware, 223 Sharp Laboratory, Newark, DE 19716, USA;Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan;Physics Department, Birla Institute of Technology and Science, Pilani 333031, India;Department of Physics and Space Sciences &SARA Observatory, Florida Institute of Technology, Melbourne, FL 32901, USA |
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| Abstract: | The pulsating DA white dwarfs are the coolest degenerate stars that undergo self-driven oscillations. Understanding their interior structure will help us 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 ?= 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. |
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| Keywords: | techniques: photometric stars: individual: EC 14012?1446 stars: oscillations stars: variables: other white dwarfs |
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