Nuclear reactions inside stars, especially exploding supernovae, create elements heavier than hydrogen and helium, the building blocks of the universe. And according to two papers published online today in Science, they do it in the amounts and forms expected by long-standing theory. One paper is the first to suggest that supernovae produce enough phosphorus, an element indispensable for life, to match the proportions that scientists see in the cosmos at large . The researchers behind the study, analyzing near-infrared emissions from the supernova remnant Cassiopeia A (which lies about 11,000 light-years from Earth), estimate that levels of phosphorus in the stellar shrapnel are about 100 times the average concentration seen throughout the Milky Way—levels that will diminish as the phosphorus and other star-forged elements disperse. The second paper is the first to detect an electrically charged compound that includes a noble gas . Specifically, the team spotted far-infrared emissions from argon hydride (ArH+) in many clumps of gas spreading from the Crab nebula (image, with crosses depicting location of data points), a supernova explosion observed in 1054 C.E. Because the argon atom was bonded to other atomic fragments, the researchers could determine the particular isotope of argon involved. As expected from theory, the argon formed in the hellish environment of a supernova explosion is argon-36 (as opposed to the predominant argon isotope found on Earth, argon-40, which is produced by the radioactive decay of potassium-40).