The Hubble Space Telescope has captured this striking image of an unusual galaxy with a bullseye structure, as nine rings surround its central point. Technically known as LEDA 1313424, the galaxy has more rings than any other known galaxy, and studying it is helping astronomers to learn how galaxies like this are created.
Along with the W. M. Keck Observatory in Hawai’i, astronomers used Hubble to see that there was not just one ring around this galaxy but many. “This was a serendipitous discovery,” said lead researcher Imad Pashaof Yale University. “I was looking at a ground-based imaging survey and when I saw a galaxy with several clear rings, I was immediately drawn to it. I had to stop to investigate it.”
The researchers believe that the structure was formed when another smaller galaxy, visible as the blue blob to the left of the rings in the image, passed right through the center of the Bullseye around 50 million years ago. The effects of this massive intersection created rings like ripples in a pond, leaving behind this structure even as the smaller galaxy moved away. Even though galaxies can frequently collide or pull each other into different configurations, it’s very rare for such a precise series of rings to be observed.
That makes it fortunate that the astronomers were able to capture the galaxy right now. “We’re catching the Bullseye at a very special moment in time,” said fellow researcher Pieter G. van Dokkum, also at Yale. “There’s a very narrow window after the impact when a galaxy like this would have so many rings.”
The structure of the Bullseye is absolutely huge, at 250,000 light-years across or two and a half times the width of the Milky Way. The researchers believe that there could have been a tenth ring at one point in the galaxy’s history, even farther out, but it has since faded away.
The evidence of this galaxy also supports a previous theory that galaxy rings would move outward in a particular pattern. The rings aren’t equally spaced, but rather get more widely spaced as they move outward. “That theory was developed for the day that someone saw so many rings,” van Dokkum said. “It is immensely gratifying to confirm this long-standing prediction with the Bullseye galaxy.”
Now, the researchers want to look for more similar ringed galaxies to see if they are found elsewhere in our universe. “Once NASA’s Nancy Grace Roman Space Telescope begins science operations, interesting objects will pop out much more easily,” van Dokkum said. “We will learn how rare these spectacular events really are.”
