RX J0822-4300 in Puppis A: A neutron star created when a massive star exploded about 3,700 years ago.
Caption: A wide-field composite view of the supernova remnant Puppis A
(X-rays from ROSAT in purple, optical data in pink) puts the motion of
the neutron star RX J0822-4300 into context. The explosion that created
the supernova may have been lop-sided, kicking the neutron star in one
direction and much of the debris in the other. The inset shows Chandra
observations spanning 5 years that clearly reveal motion over that time.
Astronomers calculate that RX J0822-4300 is moving at about 3 million
miles per hour, making it one of the fastest moving stars ever observed.
Scale: Inset is 14.5 arcsec across.
Chandra X-ray Observatory HRC Image