In a groundbreaking discovery astronomers have traced a slowly repeating burst of intense radio waves first detected in 2022 back to its origin: a red dwarf star. This lightweight star, likely in a binary orbit with a white dwarf (the dense core of an exploded star), provides new insights into the puzzling phenomenon of long-period radio transients.
The enigmatic radio signals, which repeat every 18 minutes, initially left scientists baffled. Typically, pulsars spinning neutron stars emitting radio waves rotate once per second or faster. However, a pulsar spinning this slowly shouldn’t theoretically produce detectable radio emissions, challenging existing models.
Since 2022, about ten “long-period radio transients” have been discovered, but all were located deep within the crowded core of the Milky Way, making it difficult to identify their sources.
A New Signal in the Galaxy’s Outskirts
To investigate further, astronomers used the Murchison Widefield Array in Western Australia, scanning less dense regions of the galaxy. Undergraduate student Csanad Horvath identified a new source, GLEAM-X J0704-37, which emits minute-long radio pulses repeating every 2.9 hours the slowest ever recorded.
Follow-up observations with the MeerKAT telescope in South Africa pinpointed the source: a red dwarf star. These faint stars, which constitute 70% of the Milky Way’s population, are typically invisible to the naked eye.
What’s Causing the Radio Waves?
The study suggests the red dwarf’s unseen binary companion, likely a white dwarf, is the true source of the radio emissions. The interaction between the red dwarf’s stellar wind streams of charged particles and the white dwarf’s magnetic field likely generates the radio pulses.
This dynamic resembles how the Sun’s solar wind interacts with Earth’s magnetic field, creating auroras and low-frequency radio emissions.
A Step Toward Solving the Puzzle
The system is reminiscent of AR Scorpii, where a white dwarf bombards a red dwarf with beams of radio waves. However, the newfound source is brighter and slower, suggesting there may be various systems producing long-period radio transients.
Astronomers are now focused on finding more of these sources to develop a unified model explaining their origin. Alternatively, these signals might emerge from entirely distinct astrophysical processes.
As one scientist noted, “We’ve learned the power of expecting the unexpected.” With continued sky surveys, the mystery of these cosmic signals may soon be unraveled, expanding our understanding of the universe.
