The born again (VLTP) scenario revisited: The mass of the remnants and implications for V4334 Sgr

TL;DR

This study uses 1D numerical simulations to explore the VLTP scenario across various remnant masses, successfully reproducing the observed evolution of V4334 Sgr without ad-hoc assumptions, and clarifies differences in remnant behavior based on mass.

Contribution

It provides a comprehensive analysis of remnant mass effects on VLTP evolution, aligning simulations with observations without requiring reduced mixing efficiency.

Findings

Low mass remnants ($\,M\lesssim0.6\,\mathrm{Msun}$) behave differently than higher mass remnants.

Higher mass remnants ($\gtrsim0.6\,\mathrm{Msun}$) do not expand significantly during VLTP.

Discrepancies in born again times are linked to energy released by H-burning during VLTP.

Abstract

We present 1-D numerical simulations of the very late thermal pulse (VLTP) scenario for a wide range of remnant masses. We show that by taking into account the different possible remnant masses, the observed evolution of V4334 Sgr (a.k.a. Sakurai's Object) can be reproduced within the standard 1D-MLT stellar evolutionary models without the inclusion of any $ad-hoc$ reduced mixing efficiency. Our simulations hint at a consistent picture with present observations of V4334 Sgr. From energetics, and within the standard MLT approach, we show that low mass remnants \hbox{($M\lesssim0.6$\msun)} are expected to behave markedly different than higher mass remnants \hbox{($M\gtrsim0.6$\msun)} in the sense that the latter are not expected to expand significantly as a result of the violent H-burning that takes place during the VLTP. We also assess the discrepancy in the born again times obtained by different authors by comparing the energy that can be liberated by H-burning during the VLTP event.