Where the Chemical Elements in the Universe Come From
Luciana Bianchi

Do you know you are made of star's stuff ? Do you know that the calcium in your bones was produced by powerful nuclear reactions in a big-star interior, several billion years ago ? The iron which colors the Red Rocks of Arizona, and of the planet Mars, comes from ancient supernovae that exploded long before our solar system was born.

Here is how the story goes. In the Big Bang, at the dawn of our Universe, all the matter was created basically at once. But, it mostly consisted of hydrogen and helium atoms. So, where did the variety of chemical elements that populate the periodic table come from ? To discover the answer, we must go back to when the first stars were born.

A star is a powerful nuclear energy furnace, which turns on when a huge cloud of gas and dust in the interstellar space condenses and collapses under its own weight. Then the star shines bright. The inner combustion (nuclear fusion) not only releases light and energy, it transforms the primordial "fuel" (hydrogen and helium) into other chemical elements, such as Silicon, Nitrogen, Carbon, Oxygen. But not all stars burn and produce chemical elements in the same way or in the same amounts. Which elements does a star produce? How much of them? How long does it take? It all depends on the mass of the star. CLICK HERE for a more detailed description of the life cycle of stars.

At the end of its life, when the fuel is all burned and no more reactions can take place, different things can happen to our star, again, depending on how massive it was. In some cases, part of the processed elements gets dispersed into the vast space, to form new clouds of gas and dust. Such clouds will form new stars (which in turn will produce different chemical elements...) and their planets, including life-supporting planets like our own Earth.

Here you can watch what happens throughout a star's life. First, choose the mass of your star: smaller than our Sun ? or, perhaps, five times larger? or fifty times larger? Click below to "make your own star", watch it evolve, and learn which chemical elements are produced at the end of your star's life.

Need sunshine ?

just click!
Make a small star

Some greens?
Wood? Paper?
just click!
Make a medium star

Need a hammer?
A golden ring?

just click!
Make a massive star

Interested? Want to learn a bit more about stellar evolution? CLICK HERE.
Also, if you want to read some of the new facts that astronomers found out about massive stars with the FUSE satellite, and with Hubble, click here

For some recent discoveries about supernova remnants, massive stars, or planetary nebulae, and more, search the FUSE Science Summaries page.

CREDITS: The animations in this activity were developed in collaboration with the Maryland Science Center; an interactive exhibit was also derived from this story, and it is now visible at JHU during the 'physics fair' events.