2001/04/05 by A. H. Corsico, A CORSICO, O. G. Benvenuto +3 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Emissivity #Envelope (radar) #Luminosity #Opacity #Pulsars and Gravitational Waves Research #Set (abstract data type) #Stability (learning theory) #Stellar, planetary, and galactic studies #Upper and lower bounds #Variable (mathematics) #White dwarf #astro-ph #hep-ph
paper · pdf · doi:10.1016/s1384-1076(01)00055-0
published as New Astron. 6 (2001) 197-213 · 32 pages, 14 figures, accepted for publication in New Astronomy
arxiv created 2001/04/05 · openalex publication_date 2001/06/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
White dwarfs are well studied objects. The relative simplicity of their physics allows to obtain very detailed models which can be ultimately compared with their observed properties. Among white dwarfs there is a specific class of stars, known as ZZ-Ceti objects, which have a hydrogen-rich envelope and show periodic variations in their light curves. G117-B15A belongs to this particular set of stars. The luminosity variations have been successfully explained as due to g-mode pulsations. G117-B15A has been recently claimed to be the most stable optical clock ever found, being the rate of change of its 215.2 s period very small: P= (2.3 +- 1.4)x10-15 s s-1, with a stability comparable to that of the most stable millisecond pulsars. The rate of change of the period is closely related to its cooling timescale, which can be accurately computed. In this paper we study the pulsational properties of G117-B15A and we use the observed rate of change of the period to impose constraints on the axion emissivity and, thus, to obtain a preliminary upper bound to the mass of the axion. This upper bound turns out to be 4cos2β meV at the 95% confidence level. Although there are still several observational and theoretical uncertainties, we conclude that G117-B15A is a very promising stellar object to set up constraints on particle physics.