Understanding the Cool DA White Dwarf, G29-38
Abstract
The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post main sequence evolution, along with their cooling rates, allowing us to calibrate their ages directly. The most important set of white dwarf variables to measure are the oldest of the pulsators, the cool DAVs, which have not previously been explored through asteroseismology due to their complexity and instability. Through a time-series photometry data set spanning ten years, we explore the pulsation spectrum of the cool DAV, G29-38 and find an underlying structure of 19 (not including multiplet components) normal-mode, probably l=1 pulsations amidst an abundance of time variability and linear combination modes. Modelling results are incomplete, but we suggest possible starting directions and discuss probable values for the stellar mass and hydrogen layer size. For the first time, we have made sense out of the complicated power spectra of a large-amplitude DA pulsator. We have shown its seemingly erratic set of observed frequencies can be understood in terms of a recurring set of normal-mode pulsations and their linear combinations. With this result, we have opened the interior secrets of the DAVs to future asteroseismological modelling, thereby joining the rest of the known white dwarf pulsators.
Keywords
Cite
@article{arxiv.astro-ph/9711123,
title = {Understanding the Cool DA White Dwarf, G29-38},
author = {S. J. Kleinman and R. E. Nather and D. E. Winget and J. C. Clemens and P. A. Bradley and A. Kanaan and J. L. Provencal and C. F. Claver and T. K. Watson and K. Yanagida and A. Nitta and J. S. Dixson and M. A. Wood and A. D. Grauer and B. P. Hine and G. Fontaine and James Liebert and D. J. Sullivan and D. T. Wickramasinghe and N. Achilleos. T. M. K. Marar and S. Seetha and B. N. Ashoka and E. Meistas and E. M. Leibowitz and P. Moskalik and J. Krzesinski and J. -E. Solheim and A. Bruvold and D. W. Kurtz and B. Warner and Peter Martinez and G. Vauclair and N. Dolez and M. Chevreton and M. A. Barstow and S. O. Kepler and O. Giovannini and T. Augusteijn and C. J. Hansen and S. D. Kawaler},
journal= {arXiv preprint arXiv:astro-ph/9711123},
year = {2009}
}
Comments
29 pages including 5 figures To appear in ApJ 1 Mar 98