IUE Temperatures for White Dwarf Stars in and Around the ZZ Ceti Instability Strip

Abstract

We have analyzed all the archival IUE images of the DA4 and DA5 white dwarfs with model atmosphere fluxes incorporating the quasi-molecular opacities to obtain a consistent set of temperatures for both the variables and nonvariables in and around the ZZ Ceti instability strip. We have found four nonvariable stars inside the instability strip. Taken at face value, this indicates that temperature is not the only parameter that determines if a star pulsates or not, but the large uncertainties in the temperature determinations makes it impossible for us to offer this as more than just a suggestion at the present time.