Scientific breakthrough uncovers hidden radio bursts in archival space data

Building on the expertise of researchers at Paris Observatory, an international team has developed a novel analysis method capable of uncovering previously undetectable stellar and exoplanetary signals hidden within archival radio-astronomical data. Thanks to this innovation, known as Multiplexed Interferometric Radio Spectroscopy (RIMS), scientists have discovered new radio bursts originating from dwarf stars. Some of these signals are consistent with star-planet interactions, analogous to the mechanisms responsible for auroral emissions in the Solar System. These results are published in Nature Astronomy, 27 January 2026.

 

A new use for radio astronomy archives

Modern radio telescopes collect colossal volumes of data, primarily exploited to synthesise images used to study distant galaxies and black holes. Until now, these archives had never been used to monitor, minute by minute, the variable activity of the hundreds of stars hidden within the field of view of each observation.

This is precisely what RIMS enables. The method transforms each radio observation into a simultaneous survey of hundreds or even thousands of stars, much like a net that captures many fish, where a single fishing rod would catch only one, regardless of the original instrument or scientific program.

“RIMS exploits every second of observation, in hundreds of directions across the sky. What we used to do source by source, we can now do simultaneously,” explains Dr Cyril Tasse, researcher at the Paris Observatory and lead author of the study. Dr Tasse is a former Rhodes University postdoc and remains an associate of the University. “Without this method, it would have taken nearly 180 years of targeted observations to reach the same detection level.”

 

An unprecedented harvest of stellar radio signals

By applying RIMS to more than 1.4 years of data collected by the European LOFAR radio telescope as part of the large sky survey LoTSS, the team generated no fewer than 200,000 dynamic spectra that represent the received energy as a function of time and frequency, from isolated stars or stars hosting exoplanets.

Among the signals revealed by RIMS are bursts consistent with violent stellar events, analogous to solar coronal mass ejections, published last month by the same team in Nature. Even more remarkably, some signals exhibit all the expected characteristics of magnetic star-planet interactions, a mechanism comparable to that producing certain auroral emissions on Jupiter.

“These signals were literally right in front of us for years in the LOFAR data, but because the LoTSS survey is designed to map galaxies rather than detect the ‘hiccups’ of nearby stars, they would have remained invisible without RIMS,” notes Philippe Zarka, co-lead author of the study and CNRS Research Director at Paris Observatory.

 

Toward large-scale detection of star-exoplanet interactions

These radio signatures could represent some of the first robust evidence of magnetic star-exoplanet interactions and exoplanetary aurorae, pointing to the likely existence of exoplanet magnetospheres. “Some bursts display characteristics duration, intensity, time-frequency morphology that are perfectly consistent with the scenario of a planet orbiting very close to its star, perturbing its magnetic field and producing intense radio emissions,” emphasises Philippe Zarka.

This breakthrough opens a new avenue for low-frequency radio astronomy. RIMS effectively turns every array of radio telescopes into a powerful detector of variable radio signals from nearby stars. "Processing the LoTSS data with RIMS was a pan-European effort", adds Martin Hardcastle, professor of astrophysics at the University of Hertfordshire in the UK and co-lead of the study. "Many petabytes of data were processed in computer centres in the Netherlands, Germany, Poland and the UK in order to extract the dynamic spectra. The results illustrate the value of open scientific data archives and community-led data processing."

“By mining existing observational data with novel processing techniques, an effort building on decade-long collaborations, this result shows how new scientific treasures can still be uncovered,” says Oleg Smirnov, professor at Rhodes University and at the South African Radio Astronomy Observatory. “With RIMS, we are entering an era in which magnetic interactions between stars and exoplanets can be studied on a very large scale, a decisive step toward understanding the habitability of worlds orbiting other stars,” adds Dr Tasse.

This new technique was also successfully applied to the new French low-frequency radiotelescope NenuFAR, and provided the detection of a burst from a star-planet system, recently published in Astronomy and Astrophysics (Zhang et al., A&A, 700, A140, 2025, doi:10.1051/0004-6361/202555209).

Future giant observatories, such as the Square Kilometre Array (SKA), will be able to fully exploit this new technique. They are expected to reveal thousands of new radio signals, paving the way for large-scale statistical exploration of stellar radio emissions and star–planet interactions in our galactic neighbourhood.