Binary Systems of core collapse supernova polluting a giant companion

TL;DR

This paper models binary systems where a supernova pollutes a giant companion with elements like calcium, proposing an alternative explanation for certain peculiar stars such as HV2112.

Contribution

It introduces a detailed stellar evolution model for supernova-polluted giants and estimates their galactic occurrence, offering a new perspective on peculiar stellar compositions.

Findings

Tens of SN-polluted giants are present in the Galaxy at any time.

Approximately 10 SN-polluted giants are in the Magellanic Clouds.

SN pollution could explain the high calcium abundance in HV2112.

Abstract

We examine binary systems where the more massive star, the primary, explodes as a core collapse supernova (CCSN) the secondary star is already a giant that intercepts a large fraction of the ejecta. The ejecta might pollute the secondary star with newly synthesized elements such as calcium. We use Modules for Experiments in Stellar Astrophysics (MESA) to calculate the evolution of such SN-polluted giant (SNPG) binaries. We estimate that on average at any given time tens of SNPGs are present in the Galaxy, and $\approx 10$ SNPG objects are present in the Magellanic Clouds. We speculate that the high calcium abundance of the recently discovered evolved star HV2112 in the Small Magellanic Cloud might be the result of an SNPG with a super AGB stellar secondary of a mass $\approx 9 M_\odot$. This rare SNPG scenario is an alternative explanation to HV2112 being a Thorne-{\.Z}ytkow object (TZO).