On the formation of double stars

From a calculation of Roche densities in visual binaries, it is concluded that the stars in these systems would be tidally unstable at the time of formation if they were formed with their observed separations (semi-major axes). To avoid this difficulty, it is proposed that the visual binaries are formed by the disintegration of small clusters. Binaries formed this way are shown to have some interesting upper limits to their mass ratios. Comments are also made on the differences between the processe of star and planet formation.