Measuring the evolution of the most stable optical clock G 117-B15A

2005/07/20 by S. O. Kepler, J. E. S. Costa, B. G. Castanheira +7 · 1 citation
Physics and Astronomy · #astro-ph

paper · pdf · doi:10.1086/497002

published as Astrophys.J.634:1311-1318,2005 · 22 pages, 4 figures

arxiv created 2005/07/20 · arxiv updated 2019/08/17

Abstract

We report our measurement of the rate of change of period with time dP/dt for the 215 s periodicity in the pulsating white dwarf G 117-B15A, the most stable optical clock known. After 31 years of observations, we have finally obtained a 4 sigma measurement dP/dt_observed = (4.27 +/- 0.80) x 10^-15 s/s. Taking into account the proper-motion effect of dP/dt_pm = (7.0 +/- 2.0) x 10^-16 s/s, we obtain a rate of change of period with time of dP/dt = (3.57 +/- 0.82) x 10^-15 s/s. This value is consistent with the cooling rate in our white dwarf models only for cores of C or C/O. With the refinement of the models, the observed rate of period change can be used to accurately measure the ratio of C/O in the core of the white dwarf.

Cited by

• The pulsating white dwarf G117-B15A: still the most stable optical clock known