An international team of astronomers from China, South Africa, Canada and Australia has found that the galaxy NGC 4632, 56 million light-years from Earth, is surrounded by a massive disk of gas, dust and stars. This places it in a rare class of polar ring galaxies. To work published In the scientific journal Monthly Notices of the Royal Astronomical Society (MNRAS).
Although NGC 4632 was already known to scientists, the ring around it was only now discovered. This is because the giant structure is invisible in most of the electromagnetic spectrum and can only be seen through a radio telescope. The team used the Pathfinder Science Facility located in the Western Australian desert.
The formation mechanism of galactic rings is still unknown. One theory suggests that clouds of gas and dust move through intergalactic space, accidentally orbiting a galaxy and becoming part of it. The second explanation is that galaxies can form rings by stealing matter from each other using gravity.
Astronomers noted that polar rings are found in only 0.5% of nearby galaxies today. But the discovery of the ring structure in NGC 4632 shows that such structures are not that rare in space.
“The results suggest that 1% to 3% of nearby galaxies may have gaseous polar rings, much higher than what can be seen with optical telescopes. “Galaxies with polar rings may be more common than previously thought,” said astrophysicist Nathan Degh of Queens University in Canada.
Earlier Indian astronomers accidentally discovered a rare ring galaxy.