Since the density of the disk is 108 cm - 5 or higher, most of the molecules are frozen out onto dust grains in the disk after they pass through the front. (sciencedaily.com)
Within these clouds, on the surfaces of tiny dust grains, hydrogen atoms link with oxygen to form water. (sciencedaily.com)
But how do the elements grow into «larger clumps» like cosmic dust grains? (sciencedaily.com)