A catastrophic collision between the two galaxies has created an extremely rare ring galaxy about 11 billion light-years from Earth. The weird doughnut-shaped galaxy is making stars in its giant rings, 50 times faster than the galactic galaxy we live in, earning it the ominous nickname: cosmic fire ring.
In a paper published Tuesday in the journal Nature Astronomy, an international team of scientists details the ring galaxy R5519, which was discovered after searching data from the Hubble Space Telescope and the W.M. Keck Observatory in Hawaii. Of the nearly 4,000 galaxies detected in the dataset, R5519 is one of the brightest galaxies and shows a distinct ring structure. So the team investigated further and quickly realized that they had found something unusual. “It’s a very strange thing that we’ve never seen before,” said Yuan Tiantian, an astronomer at Swinburne University in Australia and lead author of the study. The huge hole in this galaxy is caused by a head-on collision with another galaxy. “
Looking at the characteristics of R5519, Yuan and her team began to look for clues as to how it formed. They ruled out the effects of gravitational transmission or galaxy mergers on their abnormal structure, and nearby, they detected a companion galaxy, G5593. They suspect that this cosmic neighbor may have collided with R5519 about 40 million years ago in an “intruder” galaxy. The two galaxies must have collided head-on, splitting the R5519 disk and a wave of stars expanding out of the center when the G5593 dived in. If R5519 was caused by a huge collision, it would make it an extremely rare cosmic phenomenon. Only one in every 1,000 galaxies in the local universe is formed in this way. It is worth noting that the early universe was much more crowded, so it was thought that such collisions might be more common.
Astronomers also need to collect more data to determine whether the “ring of fire” was caused by a collision, rather than by natural evolution.