Evolution of Post-Impact Companion Stars in SN Ia Remnants within the Single-Degenerate Scenario

TL;DR

This study uses hydrodynamic simulations and stellar evolution models to analyze the post-impact evolution of companion stars in Type Ia supernova remnants within the single-degenerate scenario, providing insights into their observable properties.

Contribution

It presents the first detailed 3D hydrodynamic and stellar evolution modeling of post-impact companion stars, exploring their luminosity, radius, and rotation evolution over hundreds to thousands of years.

Findings

Post-impact stars significantly increase in luminosity and radius immediately after impact.

Remnant stars expand for 100-1000 years before contracting, depending on energy absorption.

Surface rotational speed can decrease to ~10 km/s, affecting observational identification.

Abstract

The nature of the progenitor systems of Type Ia supernovae is still uncertain. One way to distinguish between the single-degenerate scenario (SDS) and double-degenerate scenario (DDS) is to search for the post-impact remnant star. To examine the characteristics of the post-impact remnant star, we have carried out three-dimensional hydrodynamic simulations of supernova impacts on main sequence-like stars. We explore the evolution of the post-impact remnants using the stellar evolution code MESA. We find that the luminosity and radius of the remnant star dramatically increase just after the impact. After the explosion, post-impact companions continue to expand on a progenitor-dependent timescale of $\sim 10^{2.5-3} $ yr before contracting. It is found that the time evolution of the remnant star is dependent on not only the amount of energy absorbed, but also on the depth of the energy deposition. We examine the viability of the candidate star Tycho G as the possible remnant companion in Tycho's supernova by comparing it to the evolved post-impact remnant stars in our simulations. The closest model in our simulations has a similar effective temperature, but the luminosity and radius are twice as large. By examining the angular momentum distribution in our simulations, we find that the surface rotational speed could drop to $\sim 10$ km s$^{-1}$ if the specific angular momentum is conserved during the post-impact evolution, implying that Tycho G cannot be completely ruled out because of its low surface rotation speed.