For the last decade, an intriguing pulse of bright energy has been detected emanating from the outskirts of our Milky Way galaxy. This fascinating phenomenon occurs every three hours and lasts for about a minute, leading astronomers on an extraordinary journey of discovery. Although the source of this radio signal has now been identified, it has given birth to yet another enigma in the cosmos.

A dedicated team from the Curtin node of the International Centre for Radio Astronomy Research (ICRAR) in Australia initially discovered the radio signal while digging through archival data from the Murchison Widefield Array (MWA), a powerful radio telescope. This energy pulse, named GLEAM-X J0704-37, holds the record for being the longest-period radio transient ever observed. Most other signals fall into brief bursts lasting from several seconds to minutes.

Long-period radio transients are emerging as a captivating area of research, with various discoveries made in recent years. These signals are thought to stem from celestial bodies displaying changing magnetic fields, such as our Sun and Jupiter. The shorter signals, on the other hand, are known as radio transients, typically produced by rotating neutron stars, which are the remnants of massive stars that exploded in supernova events.

"There’s a pressing need for an optical image to truly comprehend these long-period transients," stated Natasha Hurley-Walker, an associate professor at ICRAR and the lead author of a paper detailing this discovery, published in The Astrophysical Journal Letters. She likened the view towards these transients to a scene from "2001: A Space Odyssey," humorously noting, "My god, it’s full of stars!"

Fortunately, the recently uncovered radio transient lies approximately 5,000 light-years from Earth in the Puppis constellation—a less obstructed region compared to denser areas in the galaxy. "Our discovery is located far from the Galactic Plane, with only a few stars nearby," Hurley-Walker elaborated.

With a clearer line of sight to the source, the research team used the MeerKAT telescope in South Africa to precisely identify the location of the radio waves, which pointed to a specific star. Further investigations using the SOAR observatory in Chile revealed that the star is an M dwarf, commonly known as a red dwarf star.

While identifying the source brought clarity to one aspect of the mystery, it simultaneously introduced another. "An M dwarf by itself doesn’t possess the capability to generate the amount of energy we’re observing," Hurley-Walker noted. M dwarfs, which represent about 70% of all stars in the Milky Way, are relatively low-mass and low-luminosity, with none discernible to the naked eye.

The data indicate that this M dwarf is likely part of a binary system alongside a white dwarf—essentially the remnant core of a star that has exhausted its nuclear fuel. Together, these two stellar components seem to be producing the intriguing radio emissions. "The interaction between the M dwarf and the white dwarf is likely fueling the radio pulses," said Hurley-Walker.

Although the archival data suggests that this radio transient has been emitting signals for 10 years, it is possible that it has been active unnoticed for an even longer duration. The team is eager to conduct follow-up observations of GLEAM-X J0704-37 and explore the wealth of archival data, potentially unveiling more long-period radio transients.

Could there be countless other enigmatic cosmic sources pulsing with energy across the universe? As scientists continue to investigate, the mysteries of the cosmos promise to reveal themselves—and we are just beginning to scratch the surface. Stay tuned for more discoveries that could change everything we know about the universe!