In these objects, only traces of hydrogen are found 7, 8, as large masses of hydrogen are predicted to inhibit hydrogen–helium convective mixing within the envelope 9. However, carbon is observed at the surface of a sizeable fraction of white dwarfs 3, 4, sometimes with traces of oxygen, and is thought to be dredged up from the core by a deep helium convection zone 5, 6.

These stellar cores are enveloped by a shell of helium, which in turn, is usually surrounded by a layer of hydrogen, generally prohibiting direct observation of the interior composition. Respectively) than in previous calculations for 3M_sol.White dwarfs are dense, cooling stellar embers consisting mostly of carbon and oxygen 1, or oxygen and neon (with a few per cent carbon) at higher initial stellar masses 2. Occur at significantly smaller core masses (0.584M_sol and 0.608M_sol, We find that dredge-up and the transformation into a carbon star The 14th pulse sufficient carbon has been brought to the surface to produce aĬarbon star. Thermal pulse events and we find third dredge-up after the 7th pulse.

Strong hot-bottomīurning is observed after the 5th pulse. We obtain a maximum helium luminosity of 1.7x10^9 L_solĪnd significantly deep dredge-up after the second pulse. Viscous mesh in order to improve the numerical stability of the calculations.įor the 5M_sol star, we evolve through 25 thermal pulses and their associated Structure, convective mixing and nuclear burning. Which has a fully implicit and simultaneous method for solving for the stellar Solar metallicity calculated with the Eggleton stellar evolution code (STARS), Stancliffe (IoA and 4 other authors Download PDF Abstract: We present results of the evolution of AGB stars of 3M_sol and 5M_sol with Download a PDF of the paper titled Deep Dredge-up in Intermediate-Mass TP-AGB Stars, by R.J.

Stellar evolution dredge up