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Paper: The Blue Turn in the White Dwarf Stars of Globular Clusters
Volume: 493, 19th European Workshop on White Dwarfs
Page: 385
Authors: Campos, F.; Bergeron, P.; Romero, A. D.; Kepler, S. O.; Bonatto, C. J.; Winget, D. E.; Montgomery, M. H.
Abstract: We fitted white dwarf cooling sequences to the archival data of the globular clusters NGC 6397 and 47 Tucanae, obtained with the Hubble Space Telescope (ACS). When we fit the isochrones computed with pure H atmosphere models, none of them correctly adjusts the blue turn caused by collision induced absorption in any of the clusters. Our white dwarf isochrones were calculated from full evolutionary models and white dwarf atmosphere models. Instead of assuming the mass of the white dwarf as the mass of the hydrogen free core at the first thermal pulse, our models consider the mass of the white dwarf as its mass in the cooling curve. Along with the different masses, the use of isochrones computed with atmosphere models including a mixture of H and He show an improvement to the fit of the blue turn presented by the data.
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