We
provide new white dwarf evolutionary sequences for low-metallicity
progenitors. White dwarf sequences have been derived from full
evolutionary calculations that take the entire history of progenitor
stars into account, including the thermally pulsing and the
post-asymptotic giant branch (AGB) phases. For progenitor
metallicities in the range 0.00003 ≲ Z ≲ 0.001, and in
the absence of carbon enrichment from the occurrence of a third
dredge-up episode, the resulting H envelope of the low-mass white
dwarfs is thick enough to make stable H burning the most important
energy source even at low luminosities. This has a significant impact
on white dwarf cooling times. This result is independent of the
adopted mass-loss rate during the thermally-pulsing and post-AGB
phases and in the planetary nebulae stage.
Althaus, L. G.,
Camisassa, M. E., Miller Bertolami, M. M., Córsico, A. H., &
García-Berro, E. 2015, A&A, 576, A9