An exotic phenomenon between two stars, the cause of mysterious radio signals?

Ephemeral emissions of long-lived radio waves are a new phenomenon for science. And enigmatic, because it has not been possible to clarify, at least until now, what generates them and how.

The situation may begin to change now, thanks to the discovery of one of these strange pulses of radio waves, coming from the depths of the cosmos. The discovery was made by examining archived data that was once collected by the MWA (Murchison Widefield Array), a precursor to the SKAO (Square Kilometer Array Observatory) radio astronomical observatory, in Australia.

The rare pulse occurs every three hours and lasts between 30 and 60 seconds, making this the longest-lasting ephemeral emission of radio waves among all those known, which in reality are few.

With this discovery, the researchers believe they have also identified the probable source of these emissions, which seems to clarify, to some extent, the nature of the mechanism that generates emissions of this type.

All other ephemeral emissions of long-lived radio waves detected so far came from the depths of our galaxy, that is, from places full of stars, which has made it impossible to precisely determine the cause of these radio wave emissions.

Instead, thanks to a fortunate coincidence, the new source of emissions of that class, called GLEAM-X J0704-37, was located on the outskirts of our galaxy, in a much emptier region of space, about 5,000 light-years away. away.

Because its location is far from the galactic plane, there are only a handful of stars in that area, and researchers are now sure that a particular star system is the one generating those radio waves.

The radio wave pulses sent from GLEAM-X J0704-37 were detected in data collected during observations made with the MWA (Murchison Widefield Array) radio astronomical observatory. (Photo: ICRAR / Curtin)

The research is the work of the team of Natasha Hurley-Walker and Csanád Horváth, from the International Center for Research in Radio Astronomy (ICRAR), as well as Curtin University in Australia.

At the emission point, the researchers detected a red dwarf star, spectral class M.

This discovery solved some puzzles but also raised new ones. As for the first, he clarified the origin. As for the second, it revealed a source that is difficult to accept, since, as Hurley-Walker points out, an M dwarf alone could not generate the amount of energy emitted.

M-type dwarfs are low-mass stars that have a mere fraction of the mass and luminosity of the Sun.

The authors of the study suspect that this star is accompanied by another star with stellar mass, probably a white dwarf, that is, a star in which the nuclear reactions that keep it functioning as such have ceased. Hurley-Walker and Horváth’s team believes that, together, both stars drive the strange radio wave emissions. In any case, the exact mechanism that allows this is still unclear.

After digging through the MWA archives, astronomers discovered that the GLEAM-X J0704-37 source has been active for at least ten years since the MWA began observing. However, it may have been active and undiscovered for even longer, implying that there are still many such sources to be found in data archives collected by observatories. It will not be an easy task to search for them. It must be taken into account that, for example, in the case of the MWA, its data file is no less than 55 petabytes.

The study is titled “A 2.9-hour periodic radio transient with an optical counterpart.” And it has been published in the academic journal The Astrophysical Journal Letters. (Fountain: NCYT by Amazings)