The impact of Type Ia supernova explosions on helium companions in the Chandrasekhar-mass explosion scenario

TL;DR

This study uses 3D hydrodynamical simulations to analyze how Type Ia supernova ejecta interact with helium companion stars, revealing mass stripping, enrichment, and dependencies on orbital separation and explosion energy.

Contribution

It provides detailed simulation results on ejecta-companion interactions, including mass loss, element enrichment, and the effects of explosion energy in the Chandrasekhar-mass scenario.

Findings

Only 2-5% of companion mass is stripped by SN impact.

Heavy element enrichment occurs on the companion surface.

Ejecta accumulation depends on explosion energy and orbital separation.

Abstract

In the version of the SD scenario of SNe Ia studied here, a CO WD explodes close to the Chandrasekhar limit after accreting material from a non-degenerate He companion. In the present study, we employ the Stellar GADGET code to perform 3D hydrodynamical simulations of the interaction of the SN Ia ejecta with the He companion taking into account its orbital motion and spin. It is found that only 2%--5% of the initial companion mass are stripped off from the outer layers of He companions due to the SN impact. The dependence of the unbound mass (or the kick velocity) on the orbital separation can be fitted in good approximation by a power law for a given companion model. After the SN impact, the outer layers of a He donor star are significantly enriched with heavy elements from the low-expansion-velocity tail of SN Ia ejecta. The total mass of accumulated SN-ejecta material on the companion surface reaches about > 10e-3 M_sun for different companion models. This enrichment with heavy elements provides a potential way to observationally identify the surviving companion star in SN remnants. Finally, by artificially adjusting the explosion energy of the W7 explosion model, we find that the total accumulation of SN ejecta on the companion surface is also dependent on the explosion energy with a power law relation in good approximation.