Despite the size of the galaxy, getting this image was no small feat. The Bullseye lies 567 million light-years away from Earth, making it a fairly distant object to capture in detail. But Hubble is a veteran in imaging galaxies, and a recent image reveals more rings around the Bullseye than previously known.
It has now been confirmed that the Bullseye has nine rings, eight of which are visible to Hubble. The researchers confirmed the existence of the ninth ring by studying data from the W. M. Keck Observatory. This means that the Bullseye has six more rings than any other known galaxy.
Even more compelling than the sheer number of rings around the galaxy is how they formed in the Bullseye. The researchers believe that a tiny blue dwarf galaxy flew through the Bullseye about 50 million years ago, forming the rings in the same way that a stone thrown into a pond creates ripples.
“Hubble is able to see more rings than previous observations because of its higher spatial resolution: it allows us to see separations between rings that in ground-based observations merge into a single ring,” said Pieter G. van Dokkum, an astronomer at Yale University and co-author of the study in The Astrophysical Journal Letters.
The galactic collapse caused gas, dust and stars to move in different directions, forming a rare concentric galactic structure. The blue dwarf galaxy was not destroyed in the process – in fact, it is a clump that can be seen directly to the left of the Bullseye in the image above. This is also a strange twist on the bullseye analogy, as the bullseye did not exist until the blue galaxy broke through it, causing new stars to form. Now the galaxies are about 130,000 light years apart.
“If we were to look at the galaxy directly, the rings would appear circular, with the rings clustered in the center and gradually moving further apart the further away they are,” said Imad Pasha, a doctoral student at Yale University and lead author of the study, in a NASA press release.
So, the Bullseye is not a perfect set of concentric circles. But it is still an interesting sight and a portal to the past of galactic interactions between it and its closest neighbor.
More galactic collisions may come into view with the launch of the Roman space telescope, which is expected to be in space by May 2027. “I expect that some of the most surprising results from Roman will come from simply looking at the images – when we know what to look for, machine learning, artificial intelligence, and other automated methods can discover interesting objects with incredible speed and efficiency,” said van Dokkum. “However, before we know what’s there, it’s often the human eye that highlights completely new things.”
