Here on Earth, we live on a giant magnet, created from magnetic fields flowing in the super-hot molten iron core and offering up a number of useful properties that lead to anything from protection from solar radiation to the way sea turtles navigate. But astronomers recently stumbled across a specific type of pulsar (pulsating star) called a magnetar, which has a magnetic field 100 times as strong, and now think they’ve solved the riddle of how it’s created.
Pulsars form from supernovae, when a giant and old star collapses under its own weight and then explodes outwards. Often it can leave behind a very small, very dense star, spinning incredibly fast under its own gravity. These spinning stars pulsate as they spin, sending out a characteristic electromagnetic signature into space.
But when another star orbits a pulsar, the pulsar can pull gas away from its companion, increasing its spin as it does so. The spin increases to such levels that there’s a dramatic increase in the pulsar’s magnetic field, leading to the creation of a magnetar.
Astronomers from the Open University looked at a star cluster called Westerlund 1, where a magnetar was known to reside. They identified a supergiant star that is rushing away from the cluster, suggesting it got a kick from a recent supernova explosion, and has more carbon than it should, likely a byproduct of the star’s explosion.
Simon Clark and his team have suggested that the original star was actually too large pre-explosion to remain as a pulsar, and was about to collapse into a black hole. But just before it collapsed, it expanded a little: just enough that the supergiant star could absorb some of its gas, reducing its weight and increasing its spin, and leaving it to survive as the magnetar we see today.
As thanks, what did the magnetar star do to its companion? Kicked it away with a large explosion. Nice.
[Source: Science Magazine]