Super- and massive AGB stars – IV. Final fates – initial-to-final mass relation

Abstract

We explore the final fates of massive intermediate-mass stars by computing detailed stellar models from the zero age main sequence until near the end of the thermally pulsing phase. These super-AGB and massive AGB star models are in the mass range between 5.0 and 10.0 M ⊙ for metallicities spanning the range Z=0.02−0.0001. We probe the mass limits M up , M n and M mass , the minimum masses for the onset of carbon burning, the formation of a neutron star, and the iron core-collapse supernovae respectively, to constrain the white dwarf/electron-capture supernova boundary. We provide a theoretical initial to final mass relation for the massive and ultra-massive white dwarfs and specify the mass range for the occurrence of hybrid CO(Ne) white dwarfs. We predict electron-capture supernova (EC-SN) rates for lower metallicities which are significantly lower than existing values from parametric studies in the literature. We conclude the EC-SN channel (for single stars and with the critical assumption being the choice of mass-loss rate) is very narrow in initial mass, at most ≈ 0.2 M ⊙ . This implies that between ∼ 2−5 per cent of all gravitational collapse supernova are EC-SNe in the metallicity range Z=0.02 to 0.0001. With our choice for mass-loss prescription and computed core growth rates we find, within our metallicity range, that CO cores cannot grow sufficiently massive to undergo a Type 1.5 SN explosion.

Four new massive pulsating white dwarfs including an ultramassive DAV

“…Note that the limiting mass for C/O core WDs is uncertain and it depends on the metallicity of the progenitor star. According to Doherty et al (2015), for solar metallicity, the limiting mass is between 1.075M and 1.158M .…”

A search for white dwarfs in the Galactic plane: the field and the open cluster population

“…For comparison in Fig. 9, we also plot the lifetimes for the Doherty et al (2015) super-AGB stars and the Ekström et al (2012) non-rotating models, which all fall in between the Hurley et al (2000) and BaSTI curves. A more extreme case, however, is represented by the Ekström et al (2012) rotating models, which consider an initial rotation rate on the zero-age main sequence of 0.4 times the critical escape velocity.…”

“…In the high-mass range, theoretical results show that high dredge-up efficiency couple to a moderate mass-loss (≈10 −7 M yr −1 ), during the AGB phase, and appear to dominate the evolution of white dwarf progenitors (e.g. Siess 2007Siess , 2010Doherty et al 2015). Observations suggest that the most intense core-mass growth occurs between M i = 1.6 and 3.4 M (30 per cent), while it is appears to be smaller (≈10 per cent) for stars of M i ≈ 4 M (Kalirai, Marigo & Tremblay 2014).…”

“…The evolutionary models for super-AGB stars (M i ≥ 5 M ) become very resource consuming, due to extensive time-and spatial-resolution requirements for modelling the TP-AGB phase, and some approximations are taken in to account. Stars like VPHAS J1103−5837 could help to constrain the main uncertainties in the models, due to the treatment of convection, mass-loss, and third dredge-up efficiency (Doherty et al 2015, and references therein).…”

“…In this range of masses, the separation between white dwarf and neutron star progenitors is expected to depend on stellar properties (metallicity above all; Eldridge & Tout 2004) that influence the mass growth of the core, as well as the mass-loss during the thermally pulsing AGB (TP-AGB) phase (e.g. Siess 2007Siess , 2010Doherty et al 2015).…”