A Speckle-Imaging Search for Close Triple Companions of Cataclysmic Binaries

TL;DR

This study used speckle imaging to search for close triple star companions to cataclysmic binaries, finding no main sequence companions earlier than M4V within 2-100 AU, suggesting such triples are rare.

Contribution

First direct high-resolution imaging survey targeting close triple companions of cataclysmic binaries, constraining their frequency and properties.

Findings

No main sequence companions earlier than M4V detected within 2-100 AU.

Main sequence triple companions to CVs are not very common.

Cannot rule out faint M dwarfs or brown dwarf companions.

Abstract

The orbital periods of most eclipsing cataclysmic binaries are not undergoing linear secular decreases of order a few parts per billion as expected from simple theory. Instead, they show several parts per million increases and decreases on timescales of years to decades, ascribed to magnetic effects in their donors, triple companions, or both. To directly test the triple companion hypothesis, we carried out a speckle imaging survey of six of the nearest and brightest cataclysmic variables. We found no main sequence companions earlier than spectral types M4V in the separation range 0.02" - 1.2", corresponding to projected linear separations of 2 - 100 AU, and periods of 3 - 1000 years. We conclude that main sequence triple companions to CVs are not very common, but cannot rule out the presence of the faintest M dwarfs or close brown dwarf companions.