All About Space takes a look at some of the Sun’s strangest stellar cousins
A side from the fact that the Sun is orbited by the only planet in the universe known to be home to life, it’s pretty normal as far as stars go. Along with 90 per cent of the other stars in the universe, it’s classed as ‘main sequence’ and is powered by fusing hydrogen to make helium. It’s medium sized, is using up its fuel relatively slowly and will die quite quietly – without the drama of a supernova and with no risk of leaving behind a black hole. However, some of the other stars out there are seriously strange.
In the Milky Way and its surrounding satellite galaxies, astronomers have uncovered some weird and wonderful things. There are stars shrouded in clouds of lead, stars spinning so quickly that they are almost pulling themselves apart and stars that are being eaten by their companions. And those are just the ones that we can see. Scientists have also hypothesised about the existence of even weirder objects, including stars physically inside other stars and stars orbited by alien megastructures. Here we explore some of the weird and wonderful stars in the galaxy.
1 A FROZEN STELLAR GIANT
The term ‘frozen star’ was once used by Russian scientists to describe black holes – since to an outside observer, objects crossing over the event horizon appear to freeze – but there are thought to be stars that are actually frozen. Stars release energy using nuclear fusion, smashing atoms together until their nuclei fuse and forming heavier elements in the process. The first stars in the universe were fuelled by the lightest elements – hydrogen and helium – but as the second and third generations of stars were born, these newly made heavier elements were incorporated into the gas.
In 1997, astrophysicists Fred Adams and Gregory Laughlin from the University of Michigan predicted that as the universe gets older, the stars within it will continue to become increasingly metallic, including ever increasing proportions of heavy elements. The cores of these future stars will radiate less energy, which could allow them to sustain hydrogen fusion at much lower masses. The rate of the fusion inside these small metallic stars would be so slow that the energy released would be barely sufficient to heat the surface to 0 degrees Celsius (32 degrees Fahrenheit) – the freezing point of water. These dim and long-lived stars could even be surrounded by huge clouds of ice.
2 THE STAR THAT DEFIES ALL LOGIC
Nasty 1, officially NaSt1, is a Wolf-Rayet star that’s many times the mass of our Sun and is burning through its fuel at an astonishing rate. It
