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Forged in the Hearts of Stars

ASU researchers to study what elements are created by exploding stars

Apart from hydrogen, as many have heard from the Carl Sagan and Neil deGrasse Tyson "Cosmos" series, every ingredient in the human body is made from elements forged by stars.

The calcium in our bones, the oxygen we breathe, the iron in our blood — all were forged in the element factories of stars. Even the carbon in our apple pie.

Stars are giant element furnaces. Their intense heat can cause atoms to collide, creating new elements — a process known as nuclear fusion. That process is what created chemical elements like carbon or iron, the building blocks that make up life as we know it.

It sounds pretty simple, but it is a very intricate process. And there are still many uncertainties.

Professors Sumner Starrfield and Frank Timmes, both from Arizona State University, and professor Christian Iliadis, from the University of North Carolina at Chapel Hill, hope to resolve some of those uncertainties.

“Broad brush, we have a good idea that massive stars become one kind of supernova and binary stars with white dwarfs become another type of supernova. We know a lot about what may have caused the explosions, but there are many unexplained parts that need to be worked out,” said Starrfield, Regents' Professor in ASU’s School of Earth and Space Exploration.

Inside these element factories, how much carbon for our apple pies gets made or how much calcium is available to make our bones depends on their nuclear reaction rates.

For example, as shown in the recent movie “The Martian,” if you were trying to make water, you would take hydrogen and oxygen and some energy and put it together in a container and it would make water at a certain rate depending on the temperature of the container. Add more heat, and the reaction speeds up, producing more water.

A similar thing happens inside stars — except it’s nuclear reactions releasing a factor of 1 million times more energy than a chemical reaction. Stars run on nuclear reactions. Smash together a carbon nucleus and a helium nucleus inside the furnace of a star, and out pops the oxygen we breathe. Speed up that reaction, and the star yields more oxygen.

Read the whole story here!

Nikki Cassis
School of Earth & Space Exploration