Seismological studies of ZZ Ceti stars - II. Application to the ZZ Ceti class

We used the detected pulsation modes and adiabatic pulsation models to do seismology of the class of ZZ Ceti stars and measure the H layer mass for 83 stars. We found the surface hydrogen layer to be within the range 10 -9.5 M H /M * 10 -4 , with an average of M H /M * = 10 -6.3 , which is thinner than the predicted value of M H /M * = 10 -4 , indicating that the stars lose more mass during their evolution than previously expected. These results are preliminary and do not include the possible effects of realistic C/O profiles on the fits.