The effect of {sup 22}Ne diffusion in the evolution and pulsational properties of white dwarfs with solar metallicity progenitors
- Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata (Argentina)
- Instituto de Ciencias del Espacio (CSIC), Carrer de Can Magrans s/n, E-08193, Cerdanyola del Vallés (Spain)
- Instituto de Astrofísica de La Plata, UNLP-CONICET, Paseo del Bosque s/n, 1900 La Plata (Argentina)
- Institute for Space Studies of Catalonia, c/Gran Capità 2-4, Edif. Nexus 201, E-08034 Barcelona (Spain)
Because of the large neutron excess of {sup 22}Ne, sedimentation of this isotope occurs rapidly in the interior of white dwarfs. This process releases an additional amount of energy, thus delaying the cooling times of the white dwarf. This influences the ages of different stellar populations derived using white dwarf cosmochronology. Furthermore, the overabundance of {sup 22}Ne in the inner regions of the star modifies the Brunt–Väisälä frequency, thus altering the pulsational properties of these stars. In this work we discuss the impact of {sup 22}Ne sedimentation in white dwarfs resulting from solar metallicity progenitors (Z = 0.02). We performed evolutionary calculations of white dwarfs with masses of 0.528, 0.576, 0.657, and 0.833 M{sub ⊙} derived from full evolutionary computations of their progenitor stars, starting at the zero-age main sequence all the way through the central hydrogen and helium burning, the thermally pulsing asymptotic giant branch (AGB), and post-AGB phases. Our computations show that at low luminosities (log(L/L{sub ⊙})≲−4.25), {sup 22}Ne sedimentation delays the cooling of white dwarfs with solar metallicity progenitors by about 1 Gyr. Additionally, we studied the consequences of {sup 22}Ne sedimentation on the pulsational properties of ZZ Ceti white dwarfs. We find that {sup 22}Ne sedimentation induces differences in the periods of these stars larger than the present observational uncertainties, particularly in more massive white dwarfs.
- OSTI ID:
- 22869023
- Journal Information:
- Astrophysical Journal, Vol. 823, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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