High resolution ground-based astrometry of binary stars

Abstract

Speckle interferometry is providing measures of binary systems with separations down to 30 milliarcsec and with accuracies an order of magnitude improved over visual techniques. Speckle imaging methods are being tailored to differential photometry of binary stars so that individual magnitudes and colors determined with accuracies of ±0.02 magnitude will be available for large numbers of systems, a prerequisite to the full utilization of these objects for fundamental astrophysics. While speckle methods have penetrated into the observational gap separating “visual” and “spectroscopic” binaries, long-baseline interferometry will completely eliminate the observational distinction of these classes of systems. With limiting resolutions of a fraction of a milliarcsecond, interferometric arrays will resolve the majority of the known spectroscopic binaries. Besides providing a wealth of newly determined masses, luminosities, and effective temperatures, arrays will also impact distance scales through the geometric determinations of distances to double-lined binaries at kpc distances.