Shaping the initial-final mass relation of white dwarfs with AGB outflows

Abstract

AbstractA recent analysis of a few carbon-oxygen white dwarfs in old open clusters of the Milky Way (MW) identified a kink in the initial-final mass relation (IFMR), located over a range of initial masses, 1.65 ≲ Mi/M⊙ ≲ 2.10, which unexpectedly interrupts the commonly assumed monotonic trend. The proposed interpretation links this observational fact to the formation of carbon stars and the modest outflows (with mass loss rate < 10−7M⊙/yr) that are expected as long as the carbon excess remains too low to produce dust grains in sufficient amount. Under these conditions the mass of the carbon-oxygen core can grow more than is generally predicted by stellar models. We discuss these new findings also in light of a new systematic follow-up investigation, based on Gaia EDR3, of evolved giants (13 carbon stars, 3 S stars and 4 M stars) belonging to intermediate-age open clusters.