Resolving Doubles: Diameters of the Nearest Visual Binary Stars

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

This project will precisely measure the sizes and temperatures of stars in nearby double-star systems. These stars are important, because they orbit each other but are far enough apart that they evolve just like single stars. Unlike many close binary stars, which can be distorted by each other's gravity, these wide pairs offer a clearer picture of how stars change over time. The team will use a special kind of telescope called an interferometer to measure the stars’ angular diameters, which will then be combined with information about their brightness and distance to calculate their physical sizes and temperatures. The project includes strong education and outreach components: high school students will learn about stars and build their own telescopes, and undergraduate and graduate students will receive hands-on training in modern astronomy. The research team will conduct a program of high-precision interferometric observations using the CHARA Array to measure angular diameters of stars in 14 nearby visual binary systems. The targets are selected to be spatially resolvable, wide enough to avoid tidal interactions, and have existing or emerging dynamical mass constraints. By combining angular diameters with bolometric fluxes and precise parallaxes, the project will derive effective temperatures and physical radii to within 2% precision for at least 24 stars across a broad range of masses and metallicities. This dataset will provide critical tests of modern stellar evolutionary models, including MESA, Dartmouth (standard and magnetic versions), PARSEC, SPOTS, and Lyon models. The sample’s coverage of subsolar metallicities and low masses enables targeted exploration of radius inflation trends, with special attention to metallicity effects largely inaccessible in eclipsing binary datasets. The team will also pursue methodological advances in fringe analysis for close binaries and calibration-star validation using Gemini adaptive optics imaging. The broader impact plan includes co-development of a high school curriculum module with the GSU COR This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.