| @Joe Ball: None of these systems can be resolved by eye and I'm not sure they can all be resoved directly even with large telescopes. The usual techniques, I believe, are to look for stars wobbling and changes in brightness as the components pass in front of one another or to look for the system wobbling about its centre of mass — less precise versions of the same techniques that are used today to detect extrasolar planets. It seems that most stars are, actually, parts of star systems rather than single stars. On this list, numbers 1, 3, 6, 7, 8, 11, 13, 14, 15 (nine out of fifteen) are star systems, though most of them consist of a single bright star with one or more smaller, much dimmer companions. |