For the past two decades, a mysterious cosmic signal has been pinging every 1.4 hours from the depths of space. These bursts of radio waves, known as long-period radio transients, have puzzled scientists since their discovery in 2005. Unlike typical radio waves that last mere milliseconds, these emissions persist for minutes to an hour. Now, researchers believe they have identified the cause: a 'vampire star' system.
The Vampire Star System
The source is ASKAP J1745-5051, a star system located approximately 1.116935e+16 miles from Earth. It consists of two stars: a white dwarf, the remnant of a collapsed star, and a small, dim red dwarf. The white dwarf, though no larger than Earth, is voraciously consuming material from its companion, earning the 'vampire' moniker.
Scientific Breakthrough
International researchers published their findings in Nature Astronomy, explaining that excessive material accumulating on the white dwarf's surface triggers a nova explosion, producing the radio pings. Lead author Kovi Rose, a PhD student at the University of Sydney's School of Physics, stated: 'For the first time, we have pinpointed the origin of these signals, confirming the source to be a cataclysmic variable, or an accreting white dwarf star.' He added that long-period radio transients have baffled astronomers for years, with only about a dozen discovered and their origins unclear.
X-ray Emissions and Magnetic Interactions
The white dwarf saps material from the red dwarf, heating it to millions of degrees and emitting X-rays, as observed by the Australian SKA Pathfinder radio telescope. The radio waves themselves result from interactions between the stars' magnetic fields. The pair orbits each other every 1.4 hours in an elliptical orbit, bringing them closer together before drifting apart. When they approach, their magnetic fields clash, stripping particles from each other's surfaces. These shredded particles accelerate, producing synchrotron radiation—the observed radio waves.
Implications for Future Research
Dr Alfredo Carpineti, an astronomer not involved in the study, noted that while this finding explains one transient, it may not account for all long-period radio transients. He called the discovery exciting, emphasizing the importance of connecting signals to sources. Rose described the finding as a 'stellar Rosetta stone' for future discoveries, helping differentiate types of long-period radio transients. The team plans to continue studying the system using radio, optical, and X-ray telescopes to better understand the signals. 'Each new discovery is helping us piece together the bigger picture,' Rose said. 'We're only just beginning to understand this new class of cosmic events.'
