The pulsating hydrogen atmosphere white dwarf star G 117-B15A has been observed since 1974. Its main pulsation period at 215.19738823(63) s, observed in optical light curves, varies by only (5.12 ± 0.82) × 10-15 s s-1 and shows no glitches, as pulsars do. The observed rate of period change corresponds to a change of the pulsation period by 1 s in 6.2 million yr. We demonstrate that this exceptional optical clock can continue to put stringent limits on fundamental physics, such as constraints on interaction from hypothetical dark matter particles, as well as to search for the presence of external substellar companions.
The Astrophysical Journal
- Pub Date:
- January 2021
- White dwarf stars;
- Late stellar evolution;
- Astrophysics - Solar and Stellar Astrophysics
- 14 pages, 2 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:astro-ph/0507487