'Jekyll and Hyde' behavior found in a distant double star system

Astronomers observe ‘Jekyll and Hyde’ behavior in a double star system 19,000 light-years away that switches between X-ray and radio waves

  • A dense cluster called Terzan 5 sits 19,000 light-years away from Earth
  • Experts re-analyzed an image of the system snapped back in February
  • They found that the double star system flips between X-rays and radio waves 
  • The stellar duo appears to return to its original state after a few years 

Astronomers have observed rare ‘Jekyll and Hyde’ behavior in a double star system that sits 19,000 light-years away from Earth.

Located in the cluster called Terzan 5, experts spotted a system that uses both X-rays and radio waves, and they switch between alter egos every few years.

Data shows that the neutron star orbits its lower-mass companion and pulls material from its partner’s surroundings to form a disk that emits bright X-ray light.

As material in the disk spirals toward the neutron star, it rotates faster and transforms into what is known as a millisecond pulsar star that emits pulses of radio waves detected by the Very Large Array (VLA) telescope. 

And then the the stellar duo appears to return to its original state after a few years.

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Astronomers have observed rare ‘Jekyll and Hyde’ behavior in a double star system that sits 19,000 light-years away from Earth. The image shows the binary star system CX1 in the Terzan 5 globular cluster. Low, medium and high-energy X-rays detected by the Chandra X-ray telescope are colored red, green and blue

Craig Heinke, professor in the University of Alberta’s Department of Physics, said: ‘In this study, we observed an exotic stellar binary system using both X-rays and radio waves.’

‘Only ten years ago, we knew of neutron stars that were pulsars, and neutron stars that accreted matter from companion stars, but none that switched back and forth.’

This is what was observed in pictures released in February of the system using NASA’s Chandra X-ray Observatory by scientists of the Milky-way ATCA and VLA Exploration of Radio-sources in Clusters (MAVERIC) team .

The stellar system was described in a study led by University of Alberta physics PhD graduate Arash Bahramian.

Craig Heinke, professor in the University of Alberta’s Department of Physics, said: ‘In this study, we observed an exotic stellar binary system using both X-rays and radio waves.’ ‘Only ten years ago, we knew of neutron stars that were pulsars, and neutron stars that accreted matter from companion stars, but none that switched back and forth’

Bahramian observed a normal star and dense neutron star orbit each other, and at times, stellar material is  absorbed by the denser neutron star, which is a phenomenon known as stellar vampirism.

However, at other times, the flow stops and the neutron star’s strong magnetic field accelerates particles to near light-speed that create strong radio emissions – known as a pulsar.

Gregory Sivakoff, associate professor of physics and co-investigator on the MAVERIC team, said: ‘We know of only a handful of these stars that switch between states, called transitional millisecond pulsars.’

‘We had long thought that neutron stars had to eat material from a nearby star to spin up to such fast speeds, but it was only with transitional millisecond pulsars that we found the silver bullet that proved our hypothesis was likely true.’

Data shows that the neutron star orbits its lower-mass companion and pulls material from its partner’s surroundings to form a disk that emits bright X-ray light

But there have only been three confirmed instances that astronomers have witnessed, with the first being in 2013.

‘The first of these systems discovered elicited enormous excitement, as they represented a holy grail of X-ray astronomy: to show that accreting neutron stars can ‘turn on’ as pulsars,’ said Heinke. 

‘But they have also generated a host of other questions, and it’s been very hard to find systems like this to learn more. 

‘This find opens up a new way to search for these objects as we learn more about them, and hopefully to start to unravel their mysteries.’

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