Astronomers have detected the GJ 725A radio signal, a strong 45 MHz emission coming from a red dwarf just 11.5 light-years from Earth, in the constellation Draco. The detection was made with the European radio telescope LOFAR and is described in a paper posted to arXiv on 5 November 2026, led by Henrik Edler of ASTRON, the Netherlands Institute for Radio Astronomy. The work is still a preprint, meaning it has not yet been peer-reviewed — but the authors present the detection itself as the lowest-frequency confirmed detection of a stellar system.
The signal appeared in data from a one-hour observation recorded on 11 December 2020, during a sky survey hunting for circularly polarized radio sources. It spanned 42 to 50 MHz, with a peak brightness of 135 millijansky per beam and 74% circular polarization — and it vanished abruptly above 50 MHz. That combination of high polarization, brightness and a sharp spectral cutoff points to electron cyclotron maser emission, the same process behind Jupiter's auroral radio emissions.
Three possible explanations — none confirmed
The researchers consider three scenarios. The most striking is the aurora of a giant planet not yet detected, in a distant orbit around GJ 725A. To produce the observed cutoff near 50 MHz, that world would need a magnetic field of at least 18 gauss — stronger than Jupiter's, the largest planetary magnetic field in the Solar System, at about 14 gauss. If confirmed, it would be the first detection of an exoplanet through its magnetic field, years before the planet itself is ever seen directly.
The second hypothesis is an interaction between the star and the already known rocky planet GJ 725A b, announced in 2025, with a minimum mass 2.8 times Earth's and an orbit of just 11.22 days. A similar process happens between Jupiter and its volcanic moon Io, which drives powerful electric currents and radio emissions as it crosses the planet's magnetic field.
The third possibility is that the star itself produced the signal. Red dwarfs can have intense magnetic activity, although GJ 725A looks unusually quiet compared with stars known for radio bursts, such as AD Leo.
A signal seen only once
The biggest obstacle is that the signal has been seen only once. A follow-up observation three days later found nothing. There is an uncomfortable precedent: in 2020, LOFAR detected a similar signal from GJ 1151, another quiet red dwarf, and it was never repeated despite dozens of hours of new observations.
Nothing in the signal points to an artificial origin: the researchers found no message, modulation or coded structure, and the emission spreads across about 8 MHz — while searches for technosignatures look for transmissions squeezed into a few hertz. The origin remains unexplained, and confirmation depends on catching the signal again.
To solve the mystery, the team calls for continuous monitoring of GJ 725A at ultra-low frequencies, preferably with simultaneous observations in X-rays, ultraviolet and visible light, plus a dedicated search for a wide-orbit giant planet. If the signal returns in step with a planetary orbit, the hidden-giant hypothesis will gain strength; if it follows the star's activity, the origin will be stellar.
Read also: Planet TOI-2535 b “disappears” in front of the telescope due to the tilted orbit of a hidden neighbor.
Image credit: LOFAR station at Effelsberg, Germany, next to the 100-metre radio telescope, operated by the Max Planck Institute for Radio Astronomy — image via Wikimedia Commons.
Sources: Edler et al., "Coherent radio emission at 45 MHz from the nearby planet-hosting star GJ 725A", arXiv:2611.08719 (5 November 2026); Above the Norm News, "Astronomers Detect a Strange Radio Signal From One of Earth's Closest Stars" (9 November 2026); Wikipedia, "Low-Frequency Array (LOFAR)".
Transparency note: this article was produced with the assistance of artificial intelligence, based on cross-checking scientific publications and public sources on the internet. The information was verified against the original paper on arXiv and independent coverage; readers are encouraged to consult the original sources for further detail.
By Muse
