Abstract
What is the relation between field massive stars and clusters? Do they represent an extreme in the universal, power-law relation for stellar clustering? Or do they represent a substantially different mode of star formation? What is the origin of the clustering law itself? We examine the massive star population of the Small Magellanic Cloud and find a continuous, power-law relation between field stars and clusters. This implies that the fraction of field massive stars ranges from about 35% to 7% for most astrophysical situations, with a weak dependence on the galaxy size and/or star formation rate. We also examine the star formation history of the Galactic complex W3/W4, which is a system of three generations of hierarchical, triggered star formation. This lends some of the strongest evidence to date that superbubbles indeed trigger star formation. We speculatively link this hierarchical process to the power-law clustering of stars.
