A spectroscopic quadruple as a possible progenitor of sub-Chandrasekhar Type Ia supernovae

TL;DR

This paper reports the discovery and analysis of a young quadruple star system, HD 74438, which may evolve into a sub-Chandrasekhar Type Ia supernova through white dwarf mergers, providing insights into supernova progenitors and galactic chemical evolution.

Contribution

It presents the first detailed study of a young quadruple system as a potential progenitor of sub-Chandrasekhar SNIa, combining spectroscopy and astrometry to analyze its evolution.

Findings

HD 74438 is the youngest known SB4 quadruple system.

The system's secular interactions may lead to white dwarf mergers.

This system could significantly contribute to the population of sub-Chandrasekhar SNIa.

Abstract

Binaries have received much attention as possible progenitors of Type Ia supernova (SNIa) explosions, but long-term gravitational effects in tight triple or quadruple systems could also play a key role in producing SNIa. Here we report on the properties of a spectroscopic quadruple (SB4) found within a star cluster: the 2+2 hierarchical system HD 74438. Its membership in the open cluster IC 2391 makes it the youngest (43 My) SB4 discovered so far and among the quadruple systems with the shortest outer orbital period. The eccentricity of the 6 y outer period is 0.46 and the two inner orbits, with periods of 20.5 d and 4.4 d, and eccentricities of 0.36 and 0.15, are not coplanar. Using an innovative combination of ground-based high resolution spectroscopy and Gaia/Hipparcos astrometry, we show that this system is undergoing secular interaction that likely pumped the eccentricity of one of the inner orbits higher than expected for the spectral types of its components. We compute the future evolution of HD 74438 and show that this system is an excellent candidate progenitor of sub-Chandrasekhar SNIa through white dwarf (WD) mergers. Taking into account the contribution of this specific type of SNIa better accounts for the chemical evolution of iron-peak elements in the Galaxy than considering only near Chandrasekhar-mass SNIa.