Flickering in AGB stars: Probing the nature of accreting companions

TL;DR

This study investigates flickering in AGB stars to identify accreting white dwarf companions, finding evidence in some stars and confirming the white dwarf nature of Mira's companion.

Contribution

It demonstrates the use of flickering detection as a method to distinguish between main-sequence and white dwarf companions in AGB stars.

Findings

Flickering detected in Mira and Y Gem.

No flickering observed in R Aqr and V1016 Cyg.

Mira's companion is likely a white dwarf.

Abstract

Binary companions to asymptotic giant branch (AGB) stars are an important aspect of their evolution. Few AGB companions have been detected, and in most cases it is difficult to distinguish between main-sequence and white dwarf companions. Detection of photometric flickering, a tracer of compact accretion disks around white dwarfs, can help identify the nature of these companions. In this work, we searched for flickering in four AGB stars suggested to have likely accreting companions. We found no signs for flickering in two targets: R~Aqr and V1016 Cyg. Flickering was detected in the other two stars: Mira and Y Gem. We investigated the true nature of Mira's companion using three different approaches. Our results for Mira strongly suggest that its companion is a white dwarf.