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Detecting a pulsar that tore apart a companion star

NASA announced the discovery of a rare “black widow” binary star system 3,000 light-years from Earth.





Simulation of a typical black widow binary star system.  Photo: NASA

Simulation of a typical black widow binary star system. Image: NASA

To date, only about 20 pairs of black widow binary stars are known in the Milky Way. They usually consist of a pulsar (a very fast rotating neutron star) that steals matter from the companion star. As extremely massive matter accumulates on the surface, the pulsar releases a blast of X-rays and gamma rays, which then continue its destruction.

The newly discovered pair, named ZTF J1406 + 1222 for its coordinates in the sky, is the most closely associated black widow binary star system ever, with the pulsar and its companion. it locked in an “orbital dance” for a period of just 62 minutes, according to research published in the journal Nature on 4/5.

The team from the Massachusetts Institute of Technology in the US, led by Kevin Burdge, found ZTF J1406 + 1222 in a data warehouse collected by the Palomar Observatory in California.

As the accumulating matter fell onto the pulsar, the additional angular momentum it provided accelerated the pulsar’s rotation by hundreds of revolutions per second, making it a millisecond pulsar.

The faster the pulsar rotates, the more radiation the pulsar releases, heating the opposite side of the companion star. Burdge’s team says that this creates a significant difference in brightness between the two hemispheres of the companion star. Thus, as the pulsar and companion orbit each other, we will see the star periodically brighten and dim. “So instead of looking for the pulsar directly, try looking for a companion star that’s heating up,” Burdge said.

However, ZTF J1406 + 1222 does not appear to be a typical black widow binary star system, as no X-rays or gamma rays have been detected, which are the signatures needed to confirm the object’s existence. surrounding accretion. Therefore, the system needs to be studied further.

Astronomers believe that most black widow binary star systems form inside globular clusters. If such clusters wander too close to the center of our Milky Way, the intense gravity from the supermassive black hole there could rip apart the structure and scatter the stars in the cluster across the galaxy. .

“It’s a complicated scenario. This system has probably been drifting around the Milky Way longer than our Sun,” added Burdge.

Doan Duong (According to Space)

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