spaceSpace and Physics

Pulsar Knocks Out Its Companion Star

guest author image

Caroline Reid

Guest Author

1298 Pulsar Knocks Out Its Companion Star
An artist's impression of the pulsar punching through its companion's stellar disk. NASA.

Ding ding ding ding! It's a knockout! Far out in the universe, a strange cosmic boxing match has reached a dramatic climax. On one side of the ring is a swift and rapid pulsar, spinning at roughly 20 times a second. On the other is a star that is about 30 times as massive as the Sun. And the pulsar has landed a hefty punch on the star. A punch so strong that it has blown away a chunk of the other star's gas.

The stellar duo, called B1259, is an unusual pairing in the universe. Pulsars, ultra-dense and rapidly spinning neutron stars, are sometimes the remnant of a fairly massive main sequence star exploding as a supernova. This pulsar has a powerful magnetic field and, when combined with its rotation, it generates a powerful wind of high-energy particles that are shot out into space at nearly the speed of light. 


The companion star is also spinning dangerously fast; it's close to the speed at which rotation will start to blow away the star's outer layers of dust and gas. This material that is whizzed away from the star forms a disk.

This feisty duo are locked in orbit. They reunite at their closest point every 41 months. It is at this time of least separation that the pulsar sails through the star's outer disk of gas. This is when the pulsar strikes.

“These two objects are in an unusual cosmic arrangement and have given us a chance to witness something special,” said George Pavlov, from Penn State University in State College, who was the lead author of the study published in the Astrophysical Journal. “As the pulsar moved through the disk, it appears that it punched a clump of material out and flung it away into space.” 

You can see the effects of a reunion between the pulsar and its companion star in these images.


Three images of the unusual stellar companions over 4 years. Stellar dust is seen blown away in 2013 and 2014. NASA/CXC/PSU/G.Pavlov et al.

The images themselves might not seem like much, but the piece of matter that got knocked off the star is at least a hundred times greater in size than our Solar System. While it is huge, it is also thin: the total mass of matter in there is about the same as the mass of water in Earth's oceans. So the dust is spread out very finely.

“This just shows how powerful the wind blasting off a pulsar can be,” said Jeremy Hare, from George Washington University and coauthor of the paper. “The pulsar’s wind is so strong that it could ultimately eviscerate the entire disk around its companion star over time.”

Astronomers will no doubt be keen to watch the next round of this cosmic boxing match when the pulsar swings around for another hit.


spaceSpace and Physics
  • tag
  • binary,

  • pulsar,

  • star,

  • companion