9Msun ultramassive WD stars progenitor

Using MESA r24.08.01, we calculate its entire evolution from pre-ZAMS to the WD cooling curve, including both the evolution through 139 thermal pulses and the post-AGB phase. The resulting remnant is an ultramassive H-deficient WD, for which the composition, in mass fraction, is 47.7% ^16^O, 39.7% ^20^Ne, 4.2% ^24^Mg, 3.3% ^23^Na and 0.386% ^12^C -- corresponding to a total mass of 5x10^-3^M_{sun}_ of C --, surrounded by a 1.5x10^-5^M_{sun}_ He layer.

We also investigate the effects of fully suppressing the TP-SAGB stage by adopting a high mass-loss rate only after the second dredge-up, and find only minor differences in the final mass and composition. In addition, we calculate models with and without phase separation during the WD stage, estimating a cooling delay of only 16Myr. This is the first ultramassive white dwarf sequence for which both the TP-SAGB and post-AGB stages are calculated and, to our knowledge, the most massive WD model from complete evolution for which cooling times and detailed abundance profiles are published.