Formation and Evolution of [Wolf-Rayet] Planetary Nebulae through a Late Thermal Pulse

We present radiation-hydrodynamical simulations of the formation of a born-again planetary nebula (PN) triggered by a late thermal pulse (LTP). The 2D radiation-hydrodynamic simulations, performed with the pluto code, follow the stellar and wind properties resulted from a stellar evolution model calculated with the Modules for Experiments in Stellar Astrophysics (mesa) code. This mesa model uses a mass-loss prescription tailored for H-deficient [Wolf-Rayet]([WR])-type winds during the post-LTP phase. Our stellar model reproduces the nearly complete depletion of H expected after an LTP event, while matching the observed abundances and spectral types of iconic [WR]-type central stars of PNe. The simulations show that the H-deficient LTP ejecta forms a transient double-shell structure which, after ~1000 yr, becomes fully mixed with the H-rich PN. The H-deficient ejecta mass (2.9 × 10−6 M⊙) is too small compared to the H-rich nebular mass of ~1.1 M⊙ ejected during the last phases of stellar evolution to leave a lasting imprint on the nebular abundances, predicting an H-rich PNe around a [WR] central star. The injection of LTP material into the PN drives turbulence, clump formation, and enhanced mixing, providing an explanation to the larger expansion velocities and larger turbulent nebular structures of PNe with [WR] central stars compared to those with H-rich central stars. These results provide robust support for the born-again scenario as the origin of H-deficient [WR] central stars within H-rich PNe.