Ray Norris, Professor of Applied Data Science in Astrophysics for Western Sydney, found the objects with his colleagues by using the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The astronomers made the discovery as they were mapping the night sky as part of new project called the Evolutionary Map of the Universe (EMU).
The ring-shaped objects appear to be brighter along the edges and have been called odd radio circles, or ORCs for short.
Two of the ORCs have a central galaxy and all have a diameter of about one arcmin. For comparison the Sun and Moon both have angular diameters of about 30 arcminutes as seen from the Earth.
The galaxies within the two ORCs can be seen at visible wavelengths which indicates that the objects might have been formed by those galaxies.
He offered up several different explanations as to what the ORCs may be but concluded they need more investigation.
“We speculate that they may represent a spherical shock wave from an extra-galactic transient event, or the outflow, or a remnant, from a radio galaxy viewed end-on,” he wrote.
“It is also possible that the ORCs represent a new category of a known phenomenon, such as the jets of a radio galaxy or blazar when seen end-on, down the “barrel” of the jet.
“We also acknowledge the possibility that the ORCs may represent more than one phenomenon.
“Further work is continuing to investigate the nature of these objects.”