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An improved limit for the rate of period change in the ZZ Ceti star G117-B15A or The Most Stable Optical Clock Known

Published online by Cambridge University Press:  03 August 2017

S.O. Kepler
Affiliation:
Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Brazil
D.E. Winget
Affiliation:
McDonald Observatory and Department of Astronomy, The University of Texas at Austin U.S.A.
E.L. Robinson
Affiliation:
McDonald Observatory and Department of Astronomy, The University of Texas at Austin U.S.A.
R.E. Nather
Affiliation:
McDonald Observatory and Department of Astronomy, The University of Texas at Austin U.S.A.

Abstract

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The rate of change of period with time for the g-mode pulsations in ZZ Ceti stars depends directly on the cooling timescale for a DA white dwarf, and therefore a measurement of its value can yield an evolutionary timescale for the white dwarf. We have obtained an upper limit for the rate of change of the period of the dominant pulsation in the light curve of the ZZ Ceti star G117-B15A of |dP/dt| ≤ 9.9 × 10−15 s/s at the 68% confidence level, equivalent to a timescale for period change of

Type
Chapter 5: Seismological Investigations of Compact Stars
Copyright
Copyright © Reidel 1988 

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