Astronomers spot first possible exoplanet outside our galaxy - The Guardian

The exoplanet candidate appears to be orbiting an X-ray binary – made up of a normal star and a collapsed star or black hole – with its distance from this binary roughly equivalent to the distance of Uranus from the sun.

These luminous systems typically contain a neutron star or black hole pulling in gas from a closely orbiting companion star – in this case, a star with a mass about 20 times that of the Sun.

The material near the neutron star or black hole becomes superheated and glows in X-rays.

Based on this and other information, Di Stefano and colleagues estimate that exoplanet candidate would be roughly the size of Saturn, and orbit the neutron star or black hole at about twice the distance of Saturn from the Sun – roughly equivalent to Uranus’ orbit.

Any exoplanet in the system would have had to survive the cataclysmic supernova explosion that created the neutron star or black hole from a previously existing star