Close Small snowflakes of radioactive uranium that causes huge nuclear explosions may clarify some of the world's more bizarre star blasts. (Photo : Peter Dopper) Death of the Miniature Stars As miniature stars die, they cool into husks of their old selves called white dwarfs. A recent study suggests that atoms of uranium sink to the core of these aging white dwarf stars as they cool, icing into snowflake-like crystals no larger than grains of sand. Illinois State University's theoretical physicist and study co-author Matt Caplan explained that these snowflakes can function as many of the tiniest nuclear bombs in the galaxy, becoming the force that breaks off the powder keg.