DARK STARS

These cosmic creators, powered by dark matter, could be responsible for our existence, along with the appearance of today’s universe

- Amanda Doyle

A star dies. A sudden flash of light signifies the end in a supernova explosion. This, however, is only part of the life cycle of stars, as the rich materials created during the death throes of the star are ejected into space by the supernova.

When the next generation of stars form, they sweep up the leftovers of the supernova, accreting the metals that the dying star produced – metals being the term that astronomers use for anything heavier than hydrogen and helium. Metals are important; without them, the disc of gas and dust surrounding a newly forming star could not create rocky planets. But if new stars recycle the metals produced in the deaths of old stars, what did the very first stars do?

The universe began with the Big Bang, which created the gases hydrogen and helium, trace amounts of lithium and perhaps beryllium as well. Matter began to clump together, pulling in ever more material through gravitational attraction. It may have been dark matter – the mysterious substance that has yet to be directly detected – that began to accumulate first. This then drew in the ordinary matter, the stuff we can see, such as hydrogen and helium. Together the dark and ordinary matter created what is known as a ‘minihalo’, although the name is somewhat misleading, as minihalos had masses around a million times that of our Sun.