Big Dipper 'star' actually a sextuplet system!

Theosis writes: An astronomer at the University of Rochester and his colleagues have made the surprise discovery that Alcor (one of the brightest stars in the Big Dipper) is also actually two stars, and is apparently gravitationally bound to the Mizar system, making the whole group a sextuplet. This would make the Mizar-Alcor sextuplet the second-nearest such system known. The discovery is especially surprising because Alcor is one of the most studied stars in the sky.