Asteroseismological Study on PG 0112+104 with Pure and Screened Coulomb Potential
With 78.7 days of observations by Kepler space telescope, Hermes et al. (2017) made a detailed mode identification on a hot DBV star PG 0112+104. In total, 11 likely m = 0 components with 5 triplets and 3 quintuplets were identified. Those modes can be used to constrain fitting models. A grid of main sequence stars are evolved to be white dwarfs by MESA. Being results of thermal nuclear burning, the core compositions are taken out and added into WDEC to evolve grids of DBV stars. The element diffusion effect adopting pure Coulomb potential and screened Coulomb potential are added into WDEC. Two grids of DBV star models are evolved with the two Coulomb potential scenarios. The eigenfrequencies are calculated and used to fit the 11 observed modes. Two preferredmodels with pure and screened Coulomb potential scenarios are selected. They are consistent with previous spectral and asteroseismological results. The root-mean-square residual is improved by 27%. The differences for the two scenarios are obvious at the C/O-He interface area. Long-period modes are sensitive to this area, but most of the observed modes are short-period modes. DBV stars with lots of long-period modes should be found in future work to study the effect.
The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018