🔭 Astronomers discover the origin of previously unexplained radio signals

Strange radio signals from deep space have recently been detected, and their origin may have just been understood.

A team of astronomers has discovered that these repetitive pulses actually come from a pair of stars orbiting each other. This finding, obtained through simultaneous observations across multiple wavelengths, marks an advance in understanding phenomena that remain poorly understood.


These signals, known as long-period transients, emit bright radio bursts at regular intervals, but their exact nature has long remained unclear. To date, only about a dozen of these sources have been catalogued. Most seemed associated with neutron stars, but their slow rotation posed a problem: a slowly spinning neutron star should not produce radio emission. Other hypotheses involved white dwarfs, the cooled cores of less massive stars.

The discovery of ASKAP J1745 changes the game. This new radio transient was detected using the ASKAP radio telescope in Australia. For the first time, astronomers have formally identified the origin of these pulses: it is a cataclysmic variable. This term refers to a binary system where a white dwarf and another star (often a red dwarf) orbit so closely that the white dwarf's gravity pulls matter from its companion. This accretion process generates energy in the form of X-rays.

What makes ASKAP J1745 unique is that the radio and X-ray bursts repeat at exactly the same rate, that of the two stars' orbit. Observations conducted with radio, X-ray, and optical telescopes revealed this perfect synchronization. The X-rays are produced by matter heating up as it falls onto the white dwarf, while the radio waves come from interactions between charged particles and the powerful magnetic fields of both stars.

It is like the Rosetta Stone: this cross-referenced information allows us to decipher the common mechanism behind all long-period transients.


Thanks to this discovery, researchers finally have a natural laboratory to study extreme physical phenomena: matter accretion, intense magnetic fields, and plasma flows. ASKAP J1745 is the first long-period transient to show clear signs of accretion across the entire light spectrum, from radio waves to X-rays.

This signature makes it a valuable indicator for understanding other similar sources, which are often difficult to study because they lie in dusty regions of the center of our Galaxy.

ASKAP J1745 shows that accreting binary systems are a major source of these signals. Next research will focus on searching for other similar sources, to confirm this mechanism and explore the diversity of these objects.