An interferometric view of binary stars

TL;DR

This paper reviews how interferometry, especially with the PIONIER instrument, advances the study of binary stars by enabling precise measurements of stellar properties, orbit determination, and discovery of new systems.

Contribution

It demonstrates the application of interferometry in binary star research, highlighting recent results and potential improvements with upgraded instruments.

Findings

Confirmed a dichotomy within symbiotic stars

Achieved stellar mass measurements with better than 1% precision

Discovered a new Eta Carinae-like system

Abstract

The study of binary stars is critical to apprehend many of the most interesting classes of stars. Moreover, quite often, the study of stars in binary systems is our only mean to constrain stellar properties, such as masses and radii. Unfortunately, a great fraction of the most interesting binaries are so compact that they can only be apprehended by high-resolution techniques, mostly by interferometry. I present some results highlighting the use of interferometry in the study of binary stars, from finding companions and deriving orbits, determining the mass and radius of stars, to studying mass transfer in symbiotic stars, and tackling luminous blue variables. In particular, I show how interferometric studies using the PIONIER instrument have allowed us to confirm a dichotomy within symbiotic stars, obtain masses of stars with a precision better than 1%, and help us find a new Eta Carinae-like system. I will also illustrate the benefits for the study of binary stars one would get from upgrading the VLT Interferometer so as to be able to observe in the visible range.