White dwarf evolutionary sequences for low-metallicity progenitors: The impact of third dredge-up

Abstract

We present new white dwarf evolutionary sequences for low-metallicity progenitors. White dwarf sequences have been derived from full evolutionary calculations that take into account the entire history of progenitor stars, including the thermally-pulsing and the post-asymptotic giant branch phases. We show that for progenitor metallicities in the range 0.00003--0.001, and in the absence of carbon enrichment due to 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 the planetary nebulae stage. We conclude that in the absence of third dredge-up episodes, a significant part of the evolution of low-mass white dwarfs resulting from low-metallicity progenitors is dominated by stable H burning. Our study opens the possibility of using the observed white dwarf luminosity function of low-metallicity globular clusters to constrain the efficiency of third dredge up episodes during the thermally-pulsing AGB phase of low-metallicity progenitors.

To be published in Astronomy and Astrophysics. 12 pages, 11 figures

References in corpus (6)

• Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Modeling He-rich subdwarfs through the hot-flasher Scenario
• The Physics of Crystallization from Globular Cluster White Dwarf Stars in NGC 6397
• Gravitational settling of 22Ne and white dwarf evolution
• Short-period $g$-mode pulsations in low-mass white dwarfs triggered by H shell burning

Cited by in corpus (9)

• White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14
• The white dwarf luminosity function
• Asteroseismology of ZZ Ceti stars with fully evolutionary white dwarf models: I. The impact of the uncertainties from prior evolution on the period spectrum
• Random Forest identification of the thin disk, thick disk and halo Gaia-DR2 white dwarf population
• Detection of a White Dwarf companion to a Blue Straggler Star in the outskirts of globular cluster NGC 5466 with the Ultraviolet Imaging Telescope (UVIT)
• The evolution of white dwarfs resulting from helium-enhanced, low-metallicity progenitor stars
• Discovery of a Detached, Eclipsing 40 min Period Double White Dwarf Binary and a Friend: Implications for He+CO White Dwarf Mergers
• Probing the structure of Kepler ZZ Ceti stars with full evolutionary models-based asteroseismology
• Pulsating low-mass white dwarfs in the frame of new evolutionary sequences: V. Asteroseismology of ELMV white dwarf stars