Study of the pulsations of the ZZ Ceti stars
The ZZ Ceti stars are the variable single DA white dwarfs. They are all multiperiodic, and since their periods of variation, lying between 109 s and 1186 s, are 1 to 2 orders of magnitude longer than those expected for radial pulsations in white dwarfs, their variations are believed to be due to g- or r-mode nonradial pulsations. The author observed three ZZ Ceti stars: G117-B15A, G226-29, and GD 385 and 1) deciphered their complex light curves; 2) measured the rate of change of period with time for the dominant pulsation of G117-B15A, obtaining absolute value P less than or equal to 1.45 x 10/sup -14/ s s/sup -1/ at the 68% confidence level, which makes G117-B15A the most stable optical clock known; and 3) measured the wings of the H/sub ..gamma../ line of G117-B15A with high-speed photometry. The period structure of G117-B15A is such that there is a split pulsation excited with a mean frequency at exactly 3/4 the frequency of the dominant pulsation.
- Research Organization:
- Texas Univ., Austin (USA)
- OSTI ID:
- 5903433
- Country of Publication:
- United States
- Language:
- English
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