Astronomers discover new 'odd radio circle' near the center of our galaxy

A Mysterious ring of radio light could have been created by a type of massive star with a powerful wind of radiation blowing away its outer layers, according to astronomers who made the discovery with the MeerKAT radio telescope in South Africa.

In 2019, astronomers conducting a survey with the Australian Square Kilometer Array Pathfinder telescope, or ASKAP, noticed several strange rings of radio light, undetectable at any other wavelength of light and with no obvious source. The astronomers called them 'odd radio circles', or ORCs for short.

Only a handful are currently known, but now a new ORC has been discovered that breaks all the rules.

ASKAP is a technological precursor to the Square Kilometer Array (SKA), which will be a giant array of radio dishes and antennas split between Australia and South Africa. So it's fitting that South Africa also has its own SKA precursor observatory, in the form of MeerKAT, originally the Karou Radio Telescope, based in the country's Meerkat National Park.

It was in observations made with MeerKAT in November 2022 that astronomers led by Cristobal Bordiu of Catania Observatory in Italy spotted something out of the ordinary. It was an ORC, but it's not where it is supposed to be.

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Prior to this discovery, all previous ORCs had been found at high galactic latitudes. In other words, they are high above the plane of our Milky Way galaxy, meaning that they are either very close to us within our galaxy, or they are extragalactic. Indeed, several ORCs contain a galaxy in the middle of the ring, and those ORCs are thought to have been produced by an outburst from that galaxy, perhaps from a starburst event resulting in lots of supernovas, or a merger between two supermassive black holes resulting in a pulse of energy.