Radius measurement in binary stars: simulations of intensity interferometry

TL;DR

This paper simulates intensity interferometry techniques to measure radii and separations in binary stars, demonstrating feasible parameter recovery with current technology for bright systems.

Contribution

It introduces two methods for disentangling binary star parameters from intensity interferometry data, enhancing stellar radius measurement capabilities.

Findings

Angular radii and separations are measurable for bright binaries.

Disentangling brightness ratios aids in parameter recovery.

Current instrumentation can achieve limb-darkening measurements.

Abstract

Mass and radius measurements of stars are important inputs for models of stellar structure. Binary stars are of particular interest in this regard, because astrometry and spectroscopy of a binary together provide the masses of both stars as well as the distance to the system, while interferometry can both improve the astrometry and measure the radii of the stars. In this work we simulate parameter recovery from intensity interferometry, especially the challenge of disentangling the radii of two stars from their combined interferometric signal. Two approaches are considered: separation of the visibility contributions of each star with the help of differing brightness ratios at different wavelengths, and direct fitting of the intensity correlation to a multi-parameter model. Full image reconstructions is not attempted. Measurement of angular radii, angular separation and first-order limb-darkening appears readily achievable for bright binary stars with current instrumentation.