Calibration of White Dwarf cooling sequences: theoretical uncertainty

Abstract

White Dwarf luminosities are powerful age indicators, whose calibration should be based on reliable models. We discuss the uncertainty of some chemical and physical parameters and their influence on the age estimated by means of white dwarf cooling sequences. Models at the beginning of the white dwarf sequence have been obtained on the base of progenitor evolutionary tracks computed starting from the zero age horizontal branch and for a typical halo chemical composition (Z=0.0001, Y=0.23). The uncertainties due to nuclear reaction rates, convection, mass loss and initial chemical composition are discussed. Then, various cooling sequences for a typical white dwarf mass (M=0.6 Mo) have been calculated under different assumptions on some input physics, namely: conductive opacity, contribution of the ion-electron interaction to the free energy and microscopic diffusion. Finally we present the evolution of white dwarfs having mass ranging between 0.5 and 0.9 Mo. Much effort has been spent to extend the equation of state down to the low temperature and high density regime. An analysis of the latest improvement in the physics of white dwarf interiors is presented. We conclude that at the faint end of the cooling sequence (log L/Lo=-5.5) the present overall uncertainty on the age is of the order of 20%, which correspond to about 3 Gyr. We suggest that this uncertainty could be substantially reduced by improving our knowledge of the conductive opacity (especially in the partially degenerate regime) and by fixing the internal stratification of C and O.

14 figures, accepted by ApJ

References in corpus (9)

• Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements
• Equation of state of fully ionized electron-ion plasmas. II. Extension to relativistic densities and to the solid phase
• Constraints on the Progenitors of SNeIa & Implications for the Cosmological Equation of State
• The ages of very cool hydrogen-rich white dwarfs
• The 12C(alpha,gamma)16O Reaction Rate and the Evolution of Stars in the Mass Range 0.8 < M/M(sun) < 25
• Cooling sequences and color-magnitude diagrams for cool white dwarfs with hydrogen-atmospheres
• Preliminary Constraints on 12C(alpha,gamma)16O from White Dwarf Seismology
• The White Dwarf Cooling Age of the Open Cluster NGC 2420
• Evolution of a 3 \msun star from the main sequence to the ZZ Ceti stage: the role played by element diffusion

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