A new strange radio wave has hinted at the possible nature of this phenomenon.

Since 2019, astronomers have been reporting on strange radio circles (odd radio circles, or ORCs for short). So far, only a few have been discovered. In December 2023, for instance, there were reports about six such objects. These structures are only visible through radio telescopes, which means they seemingly emit only radio waves.

The ones that have been found so far extend over a million or even one and a half million light-years. To remind you, the diameter of the disk of our Milky Way galaxy is about one hundred thousand light-years.

It turns out that these spheres primarily surround galaxies. Interestingly, they are elliptical in nature. Typically, elliptical galaxies are more massive than spiral ones and often form as a result of galactic mergers.

The cause of the radio circles is currently under investigation, but there is already an understanding that high-energy electrons emit the radio waves, which are produced by some sort of galactic-scale shockwave. Researchers just need to determine what exactly triggers such a "shock."

Recently, a team of astronomers from Australia, the UK, and South Africa reported a new discovery: another ORC located billions of light-years away from us. An article about it is posted on the Cornell University preprint server. According to the scientists, the diameter of this strange radio circle is only about 372,000 light-years, which is significantly smaller than those previously discovered.

It was found that at the center of this object there is also an elliptical galaxy. In it, a certain elongated structure and other features hint at a recent merger with another galaxy. Additionally, two companion galaxies are clearly visible, indicating gravitational interactions and the disturbances they cause. Therefore, astronomers suspect that the shockwave that created this new strange radio circle is one of the consequences of a galaxy encounter.

Regarding another sphere, astronomers previously concluded that it resulted from countless nearly simultaneous supernova explosions. When a galaxy is "bubbling with life," a massive number of new massive stars are created at once. These stars are very short-lived, and in just 10-20 million years, they all "burn out" and explode as supernovae. This stellar "baby boom" quickly turns into a grand fireworks display, and the strange radio circle, according to scientists, remains as a kind of "smoke" afterward.

Moreover, two strange radio circles are notable for being directly adjacent to each other, appearing as a sort of double structure, with an active galactic nucleus in between — a supermassive black hole at the center of a young, forming galaxy that eagerly consumes surrounding material.