Cosmic Recipe for Earthlings

 

By Dolly Setton of Discover Magazine

 

Stars cook up nearly all of the approximately 60 atomic elements in people’s bodies. But exactly how that works remains a mystery. Astrophysicists have developed cutting-edge computer simulations to grapple with an array of related puzzles:

• What were stars like when they first appeared in the universe over 13 billion years ago, starting the process of modern element production?

• What do we know about the nature of the death of massive stars — signaled by Type II supernovae — that fashion crucial elements such as calcium and oxygen?

• How might the burned-out stars called white dwarfs be brought to ruin by other stars in so-called Type Ia supernovae, inciting the fiery alchemy that yielded much of the iron in our blood and the potassium in our brains?

Scientists are still trying to figure out what triggers an individual Type Ia supernova and to determine the identity of the partner star to the exploding white dwarf. The Hubble Space Telescope’s recent discovery of the earliest known Type Ia supernova from more than 10 billion years ago, plus other results, favor a scenario in which two white dwarfs merge. 

The results indicate that crucial elements in people formed later in the history of the universe than many had expected, says David Jones, the lead astronomer on the Hubble study. “It took (very roughly) about 750 million years longer to form the first 50 percent of the iron in the modern universe.”