In order to better understand star formation and its dependence on the environment within galaxies, we have to trace the star formation on even finer scales from individual stars to larger scale structures. We can then build connections between young stars and the gas they form from on the fundamental scales of stellar associations and molecular clouds. I will show results from our PHANGS-HST (Physics at High Angular resolution in Nearby GalaxieS with the Hubble Space Telescope) Treasury Program. We have developed a method to systematically trace the hierarchical structure of young stars and identify stellar associations and trace structures on scales from 8 to 64 pc. We characterize the properties of the resulting stellar associations including sizes, SED-fit ages, masses, and reddening. I will present a first look at the correlation of our stellar associations with PHANGS ground-based H-alpha imaging and ALMA CO cloud catalogs.
Stellar Associations and Hierarchical Star Formation in Nearby Galaxies