Astronomers from Western Sydney University and a team of international experts have suggested that a mysterious recently-discovered circular ring in the Large Magellanic Cloud (LMC) could actually be an intergalactic Supernova Remnant, and not an Odd Radio Circle as previously thought.
“When we originally discovered this almost perfectly circular radio object we thought it was yet another ORC (Odd Radio Circle) but after our additional observations, it became clear that this object is much more likely to be something else,” said Professor Filipovic.
The scientific team has dubbed the discovery a "rogue" Supernova Remnant, suggesting that the mysterious space ring could be the remains of an exploded star. Large Magellanic Cloud is a satellite galaxy of the Milky Way, so the location of the ring could also indicate its intergalactic origin.
“What we’ve potentially then discovered is a unique remnant of a supernova that has expanded into a rarefied, intergalactic environment — an environment that we didn’t expect to find in such an object. Our estimates point to the age of about 2,200 to 7,100 years old.”
While ORCs are highly circular at radio wavelengths, the newly-discovered object had a flatter radio spectral index, lacked a prominent galaxy host and was also significantly larger in size. All these features prompted scientists to suggest that the ring is a different kind of object.
“The most plausible explanation is that the object is an intergalactic Supernova Remnant due to an exploded star that resided in the Large Magellanic Cloud outskirts that had undergone a single-degenerate type Ia supernova which involves the explosion of two stars orbiting each other,” Filipovic explained.
There are also other versions. For instance, the ring could be a remnant of the super-flare activity from a nearby Milky Way star, or just a larger type of ORC.