(ORDO NEWS) — The universe is not a chaotic free will. Most stars are linked into galaxies that are separated by vast, almost unimaginable distances.
The space between galaxies – intergalactic space – is sparsely populated but not entirely empty; there, too, there are occasional single stars.
For the first time, astronomers believe they have found evidence of the death of one of these lone rogue stars. Not far from the Large Magellanic Cloud, a satellite galaxy that rotates with the Milky Way, a mysterious and surprisingly neat circle emitting radio waves has been discovered that hangs in space and is called J0624-6948.
If this sounds familiar, then there is a reason for it. Recently, astronomers have been puzzled by several mysterious, radio-wave-emitting cosmic circles called Strange Radio Circles, or ORCs.
Astronomer Miroslav Filipović of the University of Western Sydney in Australia didn’t miss the resemblance.
“When we initially discovered this near-perfectly round radio object, we thought it was another ORC,” he says. “But after our additional observations, it became clear that this object is much more likely to be something else.”
ORKs were first discovered using one of the most powerful radio telescopes in the world, the Australian Square Kilometer Array Pathfinder (ASKAP) in Australia. These objects seemed huge and distant, with several defining characteristics, not the least of which is a dead center galaxy.
Scientists now believe that ROCs are the result of an energetic process in these central galaxies, although the exact nature of this process is unknown.
In fact, it is likely that ORCs are actually spheres. The reason they look like rings is because of perspective; at the edges there is a greater density of radiation along our line of sight.
However, there are a few key differences between J0624-6948 and ORC. The absence of an apparent central galaxy in J0624-6948 is important, but not decisive in itself. The spectral index of radio emission is flatter than that of the ORC, and the apparent size of J0624-6948 is also different – it is larger than that of other ORCs.
Filipović and his team considered a number of possibilities that could lead to an object similar to their observations. Among them are a much larger ORC, as well as a superflare that originated on a star near the galactic center, or a jet from a distant active supermassive black hole.
As a result, one scenario turned out to be the most consistent with the observed phenomenon.
“The most plausible explanation is that the object is an intergalactic supernova remnant from the explosion of a star on the outskirts of the Large Magellanic Cloud that underwent a single degenerative Type Ia supernova, suggesting the explosion of two stars orbiting each other,” Filipović explains.
“Potentially, we have discovered a unique [supernova] remnant that has proliferated in a rarefied intergalactic medium – a medium that we would not expect to find in such an object. Our estimates indicate an age of approximately 2,200 to 7,100 years.”
While supernova remnants don’t tend to be as beautifully rounded, this is not unprecedented. Several such examples have been documented, such as the stunning eye-shaped object SN 1987A in the Large Magellanic Cloud.
If scientists are right, J0624-6948 will be the first intergalactic supernova remnant ever identified – a bubble-like ejecta sphere expanding outward. According to the team’s measurements, the connection to the Large Magellanic Cloud makes J0624-6948 about 155 light-years across.
Follow-up observations can help resolve uncertainties. In addition, additional observations using instruments such as ASKAP and its South African counterpart MeerKAT will help identify more unusual radio circles in the sky.
Finding more will give us a better picture of their range and diversity, giving us a better chance of understanding what they are.
“These new radio telescopes can detect a range of spherical objects,” Filipović says. “Through their combination of high sensitivity, good spatial sampling and wide area coverage, they enrich our understanding of the universe.”
Contact us: [email protected]