2000/06/26 by Gilles Chabrier, G. Chabrier, P. Brassard +5 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atmosphere (unit) #Black dwarf #Blue dwarf #Hydrogen #Ion #Ionization #Physics #Stars #Stellar, planetary, and galactic studies #Thermodynamics #White dwarf #astro-ph
paper · pdf · doi:10.1086/317092
43 pages, Latex file, uses aasms4.sty, accepted for publication in ApJ (November 10 issue)
arxiv created 2000/06/26 · openalex publication_date 2000/11/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present new cooling sequences, color-magnitude diagrams, and color-color diagrams for cool white dwarfs with pure hydrogen atmospheres down to an effective temperature T eff = 1500 K. We include a more detailed treatment of the physics of the fully ionized interior, particularly an improved discussion of the thermodynamics of the temperature-dependent ion-ion and ion-electron contributions of the quantum, relativistic electron-ion plasma. The present calculations also incorporate accurate boundary conditions between the degenerate core and the outermost layers as well as updated atmosphere models including the H 2 -H 2 induced-dipole absorption. We examine the differences on the cooling time of the star arising from uncertainties in the initial carbon-oxygen profile and the core-envelope L - T c relation. The maximum time delay due to crystallization-induced chemical fractionation remains substantial, from ~1.0 Gyr for 0.5 and 1.2 M ☉ white dwarfs to ~1.5 Gyr for 0.6-0.8 M ☉ white dwarfs, even with initial stratified composition profiles, and cannot be ignored in detailed white dwarf cooling calculations. These cooling sequences provide theoretical support to search for or identify old disk or halo hydrogen-rich white dwarfs by characterizing their mass and age from their observational signatures.