On the hydrogen layer thickness in pulsating DA white dwarfs

Abstract

view Abstract Citations (48) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Hydrogen Layer Thickness in Pulsating DA White Dwarfs Fontaine, G. ; Brassard, P. ; Wesemael, F. ; Tassoul, M. Abstract We reexamine the question of the relationship between the onset of pulsational driving and the thickness of the outer hydrogen layer in ZZ Ceti stars. To this end, we solve the system of ordinary differential equations which describes the linear, nonadiabatic, nonradial pulsations of stellar models with the help of a new code based on the powerful Galerkin finite-element method of weighted residuals. We find that the theoretical blue edge temperature of the ZZ Ceti instability strip is insensitive to the hydrogen layer mass for log (base 10)(MH/M*) greater than or equal to -12. This is in line with mounting evidence that ZZ Ceti pulsators with relatively thick hydrogen layers do actually exist, but it is contrary to some previous calculations which have been widely accepted. We discuss the implications of our findings vis-a-vis current white dwarf spectral evolution models. Publication: The Astrophysical Journal Pub Date: June 1994 DOI: 10.1086/187393 Bibcode: 1994ApJ...428L..61F Keywords: Hydrogen; Pulsed Radiation; Stellar Models; Stellar Oscillations; Thickness; White Dwarf Stars; Computer Programs; Differential Equations; Eigenvectors; Finite Element Method; Galerkin Method; Mathematical Models; Nonadiabatic Conditions; Numerical Analysis; Stability; Stellar Temperature; Astrophysics; STARS: INTERIORS; STARS: OSCILLATIONS; STARS: WHITE DWARFS full text sources ADS | data products SIMBAD (6)