ZZ Piscis Austrinus (ZZ PsA): A bright red nova progenitor and the instability mass ratio of contact binary stars

TL;DR

This study analyzes the contact binary system ZZ PsA, revealing it as a potential merger candidate due to its low mass ratio and deep contact, and introduces new relationships linking primary mass to system stability.

Contribution

The paper provides the first multi-band photometric analysis of ZZ PsA and develops new relationships connecting primary mass, instability mass ratio, and contact degree in binary systems.

Findings

ZZ PsA has a very low mass ratio of 0.078.

ZZ PsA is in deep contact (>95%).

Identifies ZZ PsA as a potential merger candidate.

Abstract

ZZ PsA is a neglected bright southern contact binary system with maximum V magnitude of 9.26. We present the first multi-band photometric analysis and find the system to be in deep contact (>95%) with an extremely low mass ratio of 0.078. The primary has a mass of 1.213 M? in keeping with its reported spectral class of F6. In order to determine if ZZ PsA is a merger candidate we outline the current status regarding the instability mass ratio and develop new relationship linking the mass of the primary to the instability mass ratio of the system and the degree of contact. We find that ZZ PsA along with two other examples from the literature to be merger candidates while an additional three require further observations to be confirmed as potential merger candidates.