Wide binary stars with non-coeval components

TL;DR

This paper investigates wide binary stars with components of different ages, providing evidence that some such pairs, like HD 156331, may form through stellar capture rather than coeval formation.

Contribution

It introduces a method to estimate component masses from spectral classification and identifies wide binaries with non-coeval components, including confirmed cases.

Findings

HD 156331 has components of different ages

Spectral observations support non-coevality in some wide binaries

Capture formation is a plausible scenario for these pairs

Abstract

We have estimated masses of components of visual binaries from their spectral classification. We have selected pairs, where the less massive component looks more evolved. Spectral observations of some of such pairs were made, and at least one pair, HD~156331, was confirmed to have components of different age. Since mass exchange is excluded in wide binaries, it means that HD~156331 can be formed by the capture.