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Physicists have found an exact explanation for the signals from the ASKAP J1745 system.
Astronomers have found a new source of recurring radio bursts and were able to connect it with a particular space system for the first time. The ASKAP J1745 object turned out to be a pair of closely related stars that revolve around the general center and give out bursts in the radio and X-ray at each turn.
Published in Nature Astronomy. ASKAP J1745 refers to long-period radio transients, a rare class of sources that give bright repetitive radio signals with large intervals between bursts. The first findings appeared by chance when telescopes were viewing large parts of the sky. So far, astronomers know only about 12 such objects, and the origin of the majority remains unclear.
The main problem was that long-period transients did not fit into the usual explanations. Initially, scientists looked at slow-rotating neutron stars, or pulsars. Conventional pulsars give signals every few seconds, and some new sources were repeated about once every 20 minutes. With such a slow rotation, the neutron star, according to modern ideas, should no longer create a noticeable radio emission.
Later, attention shifted to the white dwarfs. The white dwarf is a dense cooling core of a star similar to the mass on the Sun. In the double system, the white dwarf may be near a lighter red star and pull the substance from the neighbor. Such pairs are called cataclysmic variables or accreting double systems with a white dwarf.
ASKAP J1745 was found using the Australian radio telescope ASKAP, which is managed by the national scientific agency CSIRO. The new object was the first long-period radio transient, which was able to confidently refer to cataclysmic variables. Observations in radio, optical and X-ray ranges showed that radio bursts and X-ray flares are repeated synchronously with the orbital motion of the two stars.
X-ray radiation is likely to occur due to a substance that is heated when falling on a white dwarf. Radio bursts are more difficult to explain, but the dual system gives the right conditions. Charged particles flow from one star to another, and strong magnetic fields accelerate particles and create pulsed radio emission. In strength, magnetic fields in such systems can be thousands of times higher than the field of a medical MRI scanner.
Astronomers compare ASKAP J1745 to the Rosetta Stone for Long-period Radio Transients. The Rosetta Stone helped to decipher ancient Egyptian hieroglyphs thanks to one inscription in different languages. ASKAP J1745 gives a similar hint for space: one source was able to see in several ranges at once, so the data helps to understand other strange radio signals, where only individual fragments of the picture are available.
The discovery not only explains the nature of one object, but also gives astronomers a new laboratory to study extreme physics. Plasma flows, strong magnetic fields and accretion in binary star systems create conditions that cannot be reproduced on Earth. ASKAP J1745 shows that some of the mysterious slow radio signals can not be born in single dead stars, but in tight pairs where the white dwarf pulls matter from a stellar neighbor.
Astronomers have found a new source of recurring radio bursts and were able to connect it with a particular space system for the first time. The ASKAP J1745 object turned out to be a pair of closely related stars that revolve around the general center and give out bursts in the radio and X-ray at each turn.
Published in Nature Astronomy. ASKAP J1745 refers to long-period radio transients, a rare class of sources that give bright repetitive radio signals with large intervals between bursts. The first findings appeared by chance when telescopes were viewing large parts of the sky. So far, astronomers know only about 12 such objects, and the origin of the majority remains unclear.
The main problem was that long-period transients did not fit into the usual explanations. Initially, scientists looked at slow-rotating neutron stars, or pulsars. Conventional pulsars give signals every few seconds, and some new sources were repeated about once every 20 minutes. With such a slow rotation, the neutron star, according to modern ideas, should no longer create a noticeable radio emission.
Later, attention shifted to the white dwarfs. The white dwarf is a dense cooling core of a star similar to the mass on the Sun. In the double system, the white dwarf may be near a lighter red star and pull the substance from the neighbor. Such pairs are called cataclysmic variables or accreting double systems with a white dwarf.
ASKAP J1745 was found using the Australian radio telescope ASKAP, which is managed by the national scientific agency CSIRO. The new object was the first long-period radio transient, which was able to confidently refer to cataclysmic variables. Observations in radio, optical and X-ray ranges showed that radio bursts and X-ray flares are repeated synchronously with the orbital motion of the two stars.
X-ray radiation is likely to occur due to a substance that is heated when falling on a white dwarf. Radio bursts are more difficult to explain, but the dual system gives the right conditions. Charged particles flow from one star to another, and strong magnetic fields accelerate particles and create pulsed radio emission. In strength, magnetic fields in such systems can be thousands of times higher than the field of a medical MRI scanner.
Astronomers compare ASKAP J1745 to the Rosetta Stone for Long-period Radio Transients. The Rosetta Stone helped to decipher ancient Egyptian hieroglyphs thanks to one inscription in different languages. ASKAP J1745 gives a similar hint for space: one source was able to see in several ranges at once, so the data helps to understand other strange radio signals, where only individual fragments of the picture are available.
The discovery not only explains the nature of one object, but also gives astronomers a new laboratory to study extreme physics. Plasma flows, strong magnetic fields and accretion in binary star systems create conditions that cannot be reproduced on Earth. ASKAP J1745 shows that some of the mysterious slow radio signals can not be born in single dead stars, but in tight pairs where the white dwarf pulls matter from a stellar neighbor.
