We present an asteroseismic analysis of the helium atmosphere white dwarf (a DBV) recently found in the field of view of the Kepler satellite. We analyze the 5-mode pulsation spectrum that was produced based on one month of high cadence Kepler data.
The pulsational characteristics of the star and the asteroseismic analysis strongly suggest that the star is hotter (29200 K) than the 24900 K suggested by model fits to the low S/N survey spectrum of the object. This result has profound and exciting implications for tests of the Standard Model of particle physics. Hot DBVs are expected to lose over half of their energy through the emission of plasmon neutrinos. Continuous monitoring of the star with the Kepler satellite over the course of 3 to 5 years is not only very likely to yield more modes to help constrain the asteroseismic fits, but also allow us to obtain a rate of change of any stable mode and therefore measure the emission of plasmon neutrinos.
The asteroseismic analysis of white dwarfs allows us to peer below their photospheres and determine their internal structure. At ~ 28,000 K EC20058-5234 is the hottest known pulsating helium atmosphere white dwarf. As such, it constitutes an importan
t link in the evolution of white dwarfs down the cooling track. It is also astrophysically interesting because it is at a temperature where white dwarfs are expected to cool mainly through the emission of plasmon neutrinos. In the present work, we perform an asteroseismic analysis of EC20058-5234 and place the results in the context of stellar evolution and time dependent diffusion calculations. We use a parallel genetic algorithm complemented with targeted grid searches to find the models that fit the observed periods best. Comparing our results with similar modeling of EC20058-5234s cooler cousin CBS114, we find a helium envelope thickness consistent with time dependent diffusion calculations and obtain a precise mode identification for EC20058-5234.
