The (Prehistoric) History of the Elements
Kepler's supernova. Supernovae are responsible for the formation of heavy elements; a new one was spotted last month. Image courtesy NASA.
One second after the Big Bang, our universe consisted only of protons, neutrons, electrons, and other elementary particles. Because of the high temperature (only about a billion degrees) at the time, neutrons bumped into protons to produce hydrogen nuclei, and from the first three minutes to the first 20 minutes of our universe, the hydrogen nuclei combined to make helium and even a little lithium. In short, there you have the birth of hydrogen, helium and lithium. The story of the heavier elements, however, is a little more explosive.
Scientists theorize that it wasn't until 200 million years later that our favorite heavy elements came into existence through star formation and star explosions called supernovae. We are indebted to supernovae, like the one seen last month, for their fruitful offspring; the resulting heavy elements comprise everything after lithium on the periodic table. You’ll probably notice that this includes metals (such as gold, silver, iron, and aluminum) – and more interestingly, key elements that make up the human body.
Fueled by nuclear reactions (like our very own sun), the stars in the early universe had tremendous sizes, more than 200 solar masses. Over the course of their lives (about 3 million years) these gigantic stars burned through their fuel of hydrogen and helium, which produced a chain reaction to create the first molecules of nitrogen, carbon, oxygen and most vitally, the heavy iron core. During this time, there was a constant struggle between the gravity of the star pulling inward and the gas pressure pushing outward, until the heavy iron core became too heavy and caused the entire star to collapse. Then a fantastic explosion of rich elements launched out to enable future generations of stars and even rocky beautiful planets, like Earth, filled with diverse heavy elements.
Unfortunately I was not looking at the night sky that evening in June to see history in the making, but the Weizmann Institute in Rehovot, Israel was able to capture the latest supernovae observable from our humble home. For us it happens without warning, but to the star and its surroundings there is a lot building up to this bright event.
Christy Martin is an editorial intern at CHF, and is currently working on a Ph.D. in experimental astroparticle physics at Temple University.
Weizmann Captures Images of New Supernova [Eureka Alert]
Space Science [Distillations]