Study of the pulsations of the ZZ Ceti stars
Thesis/Dissertation
·
OSTI ID:5903433
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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OSTI ID:663086