High-Resolution Astronomical Imaging: Resolving Close Binaries and Stellar Surfaces via Optical Coherence

Abstract

Due to the diffraction limit of conventional telescopes, the angular resolution of single-aperture instruments in the visible band is typically restricted to ~0.02 arcseconds, which hampers the effective resolution and imaging of close binary systems and stellar surface features. To overcome this limitation, optical interferometry has emerged as a powerful technique for high-resolution astronomical imaging, grounded in optical coherence theory and the van Cittert–Zernike theorem. By employing key technologies such as telescope arrays, baseline synthesis, closure phase calibration, and u−v plane sampling, milli-arcsecond angular resolution can be achieved, enabling precise determination of orbital parameters in close binaries, as well as accurate measurements of stellar masses and radii, while allowing direct imaging of stellar magnetic activity features such as starspots and faculae. Observational approaches are generally divided into model-fitting and image-reconstruction methods, each with distinct advantages and limitations. Nevertheless, ground-based interferometry remains constrained by atmospheric turbulence, sparse u−v plane coverage, limited sensitivity, and high computational complexity. Looking ahead, future developments are expected to focus on space-based interferometers, large-scale interferometric arrays, and artificial intelligence-assisted image reconstruction. These advancements not only enrich the fundamental database of stellar physics but also provide high-precision observational support for studies of stellar evolution, binary dynamics, and exoplanetary systems.