• THE TITANIC ERUPTIONS THAT GIVE RISE TO LIFE
• OUR STELLAR NEIGHBOURS DUE TO EXPLODE
Place your fingers on your wrist and check your pulse. You can feel the blood P pumping around your body, delivering oxygen from your head to your toes. That oxygen is ferried around by trillions of red blood cells, each just 0.008 millimetres across. The element iron plays an indispensable role in this oxygen delivery, but the universe would contain very little iron if it weren’t for a ferocious type of exploding dying star called a supernova. Without supernovae, you simply wouldn’t exist.
We often think of the Sun as the quintessential star, but it’s not massive enough to go supernova when it dies. According to Dr Christopher Frohmaier, a supernova researcher at the University of Southampton, to detonate in this most spectacular of celestial firework displays, a star needs a starting mass equivalent to at least eight Suns. The path that these massive stars follow towards their eventual demise as a supernova is inevitable. It’s triggered by a fundamental shift in the interplay between the outward pressure generated by the nuclear fusion reactions in the star’s core and gravity. “Throughout a massive star’s life, it’s in a constant balance between these forces,” says Frohmaier.
Things begin to change when the hydrogen that sustains the nuclear reactions runs out. “The star will burn sequentially heavier and heavier elements to support its outer layers,” Frohmaier says. Nested shells of helium, carbon, oxygen, neon, magnesium and silicon build up as the star exhausts its supply of successive elements and desperately scrambles for something new to burn. Eventually, the star’s nuclear reactions produce iron
