A team of U.S. astronomers has observed a binary pair of white dwarfs where one star is actively devouring material from the other. Led by Emma Chickles at MIT, the researchers revealed one of the clearest views yet of how ultracompact white dwarf binaries exchange mass at extreme orbital periods—offering an enticing potential target for future generations of gravitational wave detectors. The research has been published in The Astrophysical Journal.
Binary cannibals
Binary star systems will often play host to dramatic and violent processes where one star deforms and even devours material from its companion. Yet in systems where stars orbit extremely close to one another, astronomers are still uncertain as to just how extreme these mass transfers can get.
For decades, open questions have surrounded compact binary systems containing white dwarfs: hot, bright cores that are similar in size to Earth, but which retain masses similar to living stars. These are the remnants left behind when sun-like stars exhaust their nuclear fuel and shed their outer layers entirely.
“Even these burnt-out cores can be stripped apart under the right conditions,” Chickles explains. “How this actually plays out on orbits shorter than 10 minutes is still largely unknown, and every mass-transferring binary we’ve caught at these extreme periods looks different from the last.”
Combing through stars
To shed new light on this mystery, Chickles’ team combed through millions of images of binary stars, photographed repeatedly over the past decade by a variety of stellar surveys. Through an exhaustive algorithmic approach, they were able to capture minute changes in brightness that had eluded previous studies. This hinted at the possibility of mass being transferred from bright objects as small as single white dwarfs.
“To follow up on this one, I flew out to the Magellan telescopes in Chile to work on a new high-speed camera called proto-Lightspeed,” Chickles says. “Pointing at the system, I could actually watch the light rising and falling in real time as the two stars eclipsed each other.”
Tearing away gas
This careful analysis yielded one particularly promising candidate, captured by the ATLAS survey. Named ATLAS J1013−4516, this system contains a binary pair of white dwarfs that orbit around one another in just over 8.5 minutes.
Yet as this gravitational dance plays out, one star is actively being torn apart by the other. In the process, it siphons material from a binary companion with an interior density some 250 higher than lead, and transfers it onto the forming a compact, superheated accretion disk with a comparable size to Saturn, and heated to temperatures far above those found on the surface of the sun.
“Because the system eclipses from our line of sight, we literally watch one star slide in front of the other every orbit, letting us weigh and measure the pair with a precision you almost never get for objects this exotic,” Chickles explains.
Targets for LISA
By observing this theatrical system in more detail, Chickles and her colleagues were finally able to capture a process that, despite proving so elusive so far, is likely to be widespread across the universe.
In turn, their results could lay important groundwork for future observations by LISA—the upcoming space-based counterpart to the LIGO interferometer, which has now observed hundreds of gravitational waves emanating from binary pairs of black holes and neutron stars.
Due for launch in the 2030s, LISA will be able to detect gravitational waves in unprecedented detail, perhaps being sensitive enough to capture the ripples in spacetime created by orbiting objects as small as white dwarfs.
“The system is on the short list of binaries that LISA should detect directly,” Chickles explains. “And if we found one this extreme already, many more are likely sitting in archives we already have; we just need better ways to look.”
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Publication details
Emma T. Chickles et al, An Eclipsing 8.56 Minutes Orbital Period Mass-transferring Binary, The Astrophysical Journal (2026). DOI: 10.3847/1538-4357/ae4871
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Extreme 8.5-minute orbit reveals white dwarf being torn apart by its binary companion (2026, May 23)
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