The physical properties of the ZZ Ceti stars and their pulsations

Abstract

view Abstract Citations (66) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The physical properties of the ZZ Ceti stars and their pulsations. McGraw, J. T. Abstract Stromgren colors for the ZZ Ceti variables are used to fix the mean positions of individual stars in the H-R diagram. The ZZ Ceti stars are found to be normal white dwarfs occurring in the temperature range from about 10,500 K to 13,500 K on the DA cooling sequence. The onset of variability among DA white dwarfs is shown to be an evolutionary effect occurring at the maximum of hydrogen capacity on the DA sequence. Time-resolved Stromgren photometry is used to examine the changes of the effective temperature, the radius, and the effective surface gravity with time during a pulsation to evaluate the relative contribution of these parameters to the total luminosity variation. The increase in effective temperature during a pulsation is observed to be sufficient to account for the entire change in luminosity. Changes in the radius of the star and the effective gravity during a pulsation are shown to be small. It is suggested that the partial ionization zones associated with the high opacity provide the driving mechanism for the ZZ Ceti stars. Publication: The Astrophysical Journal Pub Date: April 1979 DOI: 10.1086/156946 Bibcode: 1979ApJ...229..203M Keywords: Hertzsprung-Russell Diagram; Pulsed Radiation; Stellar Evolution; Variable Stars; White Dwarf Stars; Physical Properties; Radii; Stellar Gravitation; Stellar Luminosity; Stellar Spectrophotometry; Astrophysics; HR Diagrams:White Dwarfs; Pulsating Variables:White Dwarfs; Stroemgren Photometry:White Dwarfs; Two-Color Diagrams:White Dwarfs full text sources ADS | data products SIMBAD (10)