The pulsar PSR B1259-63 plunges into the ring of Be star SS 2883 twice during its 3.4-year elliptical orbit. The plunges are only a few months apart, just before and after periastron, the point when the two objects in orbit are closest to each other.
It is during the plunges that X-rays and gamma rays are emitted. The XMM-Newton observatory detects X-rays as seen on the background image.