Binary Evolution Pathways to Blue Large-Amplitude Pulsators: Insights from HD 133729

TL;DR

This paper models the binary evolution of HD 133729, the first confirmed BLAP in a binary, revealing its formation pathway involves non-conservative mass transfer and predicting surface elemental enhancements.

Contribution

It provides the first detailed binary evolution scenario for a BLAP with a main sequence companion, highlighting the role of non-conservative mass transfer and predicting surface abundance changes.

Findings

HD 133729 likely formed through non-conservative mass transfer in a binary system.

The system will undergo a common envelope phase leading to a merger.

Surface helium and nitrogen are enhanced on the main sequence star.

Abstract

Blue Large-Amplitude Pulsators (BLAPs) represent a recently identified class of pulsating stars distinguished by their short pulsation periods ($2 - 60$ minutes) and asymmetric light curves. This study investigated the evolutionary channel of HD 133729 which is the first confirmed BLAP in a binary system. Using the binary evolution code MESA, we explored various mass ratios and initial orbital periods. Our simulations suggest that a system with a mass ratio $q = 0.30$ undergoing non-conservative mass transfer ($\beta=0.15$) can reproduce the observed characteristics through the pre-white dwarf Roche lobe overflow channel. Meanwhile, we predict that there are significant helium and nitrogen enhancements on the surface of the main sequence (MS) star. The system will eventually undergo the common envelope phase, leading to a stellar merger. HD 133729 is a unique case as a benchmark, providing crucial insights into the formation mechanism and evolutionary fate of BLAPs with MS companions. This work constrains the elemental abundances of the MS star and has helped our understanding of non-conservative mass transfer in binary evolution.