Whip It Good! Star's Radiation Beam Sparks Cosmic Light Show

A white dwarf star (the remains of a star that has run out of fuel) is whipping its companion with a beam of radiation. This artist's impression shows the pummeled companion in the foreground.
A white dwarf star (the remains of a star that has run out of fuel) is whipping its companion with a beam of radiation. This artist's impression shows the pummeled companion in the foreground. (Image credit: M. Garlick/University of Warwick/ESO)

Move over, Devo! A distant star is whipping its companion with radiation, making the whole system pulse like an '80s power-pop dance party.

The whipping culprit is a white dwarf star (the collapsed remains of a star that ran out of fuel) that's energizing nearby electrons and accelerating them up to almost the speed of light, creating a beam of radiation, according to a statement from the European Southern Observatory. As the white dwarf spins like a record, the radiation beam whips around with the star, and slaps the nearby companion, a red dwarf star. This apparently causes the entire system, known as AR Scorpii, to release intense pulses of radiation.

"AR Scorpii was discovered over 40 years ago, but its true nature was not suspected until we started observing it in 2015," said Tom Marsh, an astrophysicist at the University of Warwick and lead researcher on the recent investigation of AR Scorpii, in the statement from ESO. "We realized we were seeing something extraordinary within minutes of starting the observations." [Top 10 Strangest Things in Space]

The two stars are orbiting each other every 3.6 hours "in a cosmic dance as regular as clockwork," according to the statement. The dramatic pulses of radiation are seen every 2 minutes, in a range of energies, from ultraviolet light to radio waves. These temper-tantrum pulses are " unlike anything ... ever encountered," said the ESO statement.

A white dwarf star (the remains of a star that has run out of fuel) is whipping its companion with a beam of radiation. This artist's impression shows the pummeled companion in the foreground. (Image credit: M. Garlick/University of Warwick/ESO)

The strange behavior of this double-star system, known as AR Scorpii, was first identified in May by a group of amateur astronomers. Follow-up observation using ESO's Very Large Telescope in Chile, as well as several other observatories, uncovered the mechanism behind the regular radiation pulses.

One aspect that makes the system particularly strange is that it is pulsing in radio frequencies; scientists have never seen this before from a white dwarf system, the statement said.

Weirder still, astronomers aren't sure which of the two stars is providing the electrons that are accelerated by the white dwarf. Right now, scientists can see only the radiation released by the system, which is typical of electrons accelerated in magnetic fields, the statement said. This is very likely the fault of the spinning white dwarf, as these objects are known to have extremely strong magnetic fields.

"Similar pulsing behavior has been observed before, but from neutron stars — some of the densest celestial objects known in the universe — rather than white dwarfs," according to the statement.

In the 1970s, AR Scorpii was initially misidentified as a single variable star. The new observations change that conclusion. A study detailing the new view of AR Scorpii was published online today (July 27) in the journal Nature.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace