Vetting the Lobster Diagram: Searching for Unseen Companions in Wide Binaries using NASA Space Exoplanet Missions

TL;DR

This study introduces the Lobster diagram method to identify unresolved companions in wide binary systems using Gaia data and space telescope archives, revealing a high multiplicity fraction among K+K binaries.

Contribution

The paper presents a novel approach combining the Lobster diagram with space-based light curve analysis to detect unseen companions in wide binaries.

Findings

78.9% of eclipsing binaries are overluminous in the Lobster diagram

73.5% of fast rotators show overluminous components

Revised lower limit on higher-order multiplicity fraction is 40.0%

Abstract

Over the past decade, the number of known wide binary systems has exponentially expanded thanks to the release of data from the Gaia Mission. Some of these wide binary systems are actually higher-order multiples, where one of the components is an unresolved binary itself. One way to search for these systems is by identifying overluminous components in the systems. In this study, we examine 4947 K+K wide binary pairs from the SUPERWIDE catalog and quantify the relative color and luminosity of the components to find evidence for additional, unresolved companions. The method is best illustrated in a graph we call the "Lobster diagram." To confirm that the identified overluminous components are close binary systems, we cross-match our wide binaries with the TESS, K2 and Kepler archives and search for the signs of eclipses and fast stellar rotation modulation in the light curves. We find that $78.9\%\pm20.7\%$ of the wide binaries which contain an eclipsing system are identified to be overluminous in the "Lobster Diagram" and $73.5\%\pm12.4\%$ of the wide binaries which contain a component showing fast rotation ($P<5$) days also show an overluminous component. From these results, we calculate a revised lower limit on the higher-order multiplicity fraction for K+K wide binaries of $40.0\%\pm1.6\%$. We also examine the higher-order multiplicity fraction as a function of projected physical separation and metallicity. The fraction is unusually constant as a function of projected physical separation while we see no statistically significant evidence that the fraction varies with metallicity.