The Initial-Final Mass Relation for Hydrogen-Deficient White Dwarfs

Abstract

The initial-final mass relation (IFMR) represents the total mass lost by a star during the entirety of its evolution from the zero age main sequence to the white dwarf cooling track. The semi-empirical IFMR is largely based on observations of DA white dwarfs, the most common spectral type of white dwarf and the simplest atmosphere to model. We present a first derivation of the semi-empirical IFMR for hydrogen deficient white dwarfs (non-DA) in open star clusters. We identify a possible discrepancy between the DA and non-DA IFMRs, with non-DA white dwarfs ≈ 0.07 M less massive at a given initial mass. Such a discrepancy is unexpected based on theoretical models of non-DA formation and observations of field white dwarf mass distributions. If real, the discrepancy is likely due to enhanced mass loss during the final thermal pulse and renewed post-AGB evolution of the star. However, we are dubious that the mass discrepancy is physical and instead is due to the small sample size, to systematic issues in model atmospheres of non-DAs, and to the uncertain evolutionary history of Procyon B (spectral type DQZ). A significantly larger sample size is needed to test these assertions. In addition, we also present Monte Carlo models of the correlated errors for DA and non-DA white dwarfs in the initial-final mass plane. We find the

Hot Degenerates in the MCT Survey. III. A Sample of White Dwarf Stars in the Southern Hemisphere

“…Note that in principle, similar 3D corrections should also be applied to DB white dwarfs (Cukanovaite et al 2021). However, as discussed by Cukanovaite et al, given the uncertainties in the microphysical calculations of DB model atmospheres, these 3D corrections are likely to change, and we simply refrain from applying them to the DB parameters in Table 2 (see also Barnett et al 2021).…”