Maximum Separations among Cataloged Binaries

The author classified many of the widest common-motion binaries listed in the Aitken catalog and lists 72 physical pairs with known photoelectric photometry, 31 physical pairs without good photometry, and 27 optical pairs. It is found that as a function of primary types, the physical systems have upper limits to their separations that are exceeded by some of the optical pairs. The fact that optical pairs occur with larger separations implies that the limits are real ones and not just catalog limitations. Those limits (in AU) are expressed by 2500 M₁^1.54 (M₁ mass of the primary in solar units) for B5 - K0 main-sequence primaries.