A Binary Progenitor for the Type IIb Supernova 2011dh in M51

TL;DR

This paper models a binary star system as the progenitor of supernova 2011dh, showing that a close binary with specific properties can explain observed pre-explosion data and supernova characteristics.

Contribution

The study presents a detailed binary stellar evolution model that matches observational constraints for SN 2011dh's progenitor, highlighting the importance of binary interactions.

Findings

Proposed binary system with 16 Msun + 10 Msun stars fits pre-explosion data.

Primary star ends as a yellow supergiant with ~4 Msun and low hydrogen content.

Secondary star remains near zero-age main sequence and is marginally detectable.

Abstract

We perform binary stellar evolutionary calculations following the simultaneous evolution of both stars in the system to study a potential progenitor system for the Type IIb supernova 2011dh. Pre-explosion photometry as well as light-curve modeling have provided constraints on the physical properties of the progenitor system. Here we present a close binary system that is compatible with such constraints. The system is formed by stars of solar composition with 16 Msun + 10 Msun on a circular orbit with an initial period of 125 days. The primary star ends its evolution as a yellow supergiant with a mass of ~4 Msun, a final hydrogen content of ~3-5E-03 Msun and with an effective temperature and luminosity in agreement with the HST pre-explosion observations of SN 2011dh. These results are nearly insensitive to the adopted accretion efficiency factor beta. At the time of explosion, the companion star has an effective temperature of 22 to 40 thousand Kelvin, depending on the value of beta, and lies near the zero age main sequence. Considering the uncertainties in the HST pre-SN photometry the secondary star is only marginally detectable in the bluest observed band. Close binary systems, as opposed to single stars, provide a natural frame to explain the properties of SN 2011dh.