Young star-caseous complexes of the Galaxy

It is found that about 90% of young clusters 0 - b2 and OB-association situated within 3 kpc from the Sun are unified into complexes with diameters from 150 to 700 pc. Almost all complexes contain giant molecular clouds with masses more than 105 Msun. A number of complexes (mostly large ones)-are connected with giant HI clouds: a few of small complexes are situated in the HI-caverns. Older (>b2) clusters avoid the regions occupied by young star groups. Complexes often have an hierarchic structure; some neighbouring complexes may be united into supercomplexes with diameter about 1.5 kpc. The concentration of OB-associations and young stellar groups into star complexes is apparently explained by their common origin in the supergiant gaseous clouds