Levels of phosphorus 100 times higher than in other parts of the Milky Way have been found in the remains of a supernova called Casseiopeia A, providing strong evidence that the phosphorus was created by the stellar explosion, reports a new study published Thursday online in Science.

Phosphorus is one of the six essential elements for life. The others are hydrogen, carbon, nitrogen, oxygen and sulphur. Hydrogen is the most abundant element in the universe and makes up most of the gas in young stars like our sun. The other essential elements, other than phosphorus, had been measured in and were confirmed to originate from nuclear processes inside stars, including supernovas.

Theoretically, phosphorus should also come from nuclear reactions inside a star, said Dae-Sik Moon, a professor of astronomy and astrophysics at the University of Toronto who co-authored the paper.