Using data from the NASA/ESA Hubble Space Telescope and the the Keck Cosmic Web Imager (KCWI) at W.M. Keck Observatory, astronomers have identified nine rings — more than previously detected by any telescope in any galaxy — around the collisional ring galaxy LEDA 1313424.
Pasha et al. detected nine rings around LEDA 1313424, a ring galaxy approximately 567 million light-years away in the constellation of Pisces. They also confirmed which galaxy dove through LEDA 1313424, creating these rings: the blue dwarf galaxy that sits to its immediate center-left. Image credit: NASA / ESA / Hubble / Imad Pasha & Pieter van Dokkum, Yale University.
LEDA 1313424 is a ring galaxy discovered in 2019 in the images from the Legacy Survey DR9.
Nicknamed the Bullseye, the galaxy has a redshift of z=0.0394, corresponding to a distance of 567 million light-years.
LEDA 1313424 has a diameter of 250,000 light-years — almost two-and-a-half times larger than our Milky Way Galaxy.
“This was a serendipitous discovery,” said Imad Pasha, a doctoral student at 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.”
A small blue dwarf galaxy traveled like a dart through the core of LEDA 1313424 about 50 million years ago.
The collision created ten rings around LEDA 1313424, an unprecedented nine of which are detected.
A thin trail of gas now links the pair, though they are currently separated by 130,000 light-years.
“We’re catching the Bullseye at a very special moment in time,” said Yale University’s Professor Pieter van Dokkum.
“There’s a very narrow window after the impact when a galaxy like this would have so many rings.”
The researchers used Hubble’s crisp vision to carefully to pinpoint the location of eight of LEDA 1313424’s rings and also used Keck to confirm one more ring.
They also found a stunning connection between the ring galaxy and a long-established theory: the galaxy’s rings appear to have moved outward almost exactly as predicted by models.
“That theory was developed for the day that someone saw so many rings,” Professor van Dokkum said.
“It is immensely gratifying to confirm this long-standing prediction with the Bullseye galaxy.”
If viewed from above, it would be more obvious that the galaxy’s rings aren’t evenly spaced like those on a dart board. Hubble’s image shows the galaxy from a slight angle.
“If we were to look down at the galaxy directly, the rings would look circular, with rings bunched up at the center and gradually becoming more spaced out the farther out they are,” Pasha explained.
A paper about this discovery was published today in the Astrophysical Journal Letters.
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Imad Pasha et al. 2025. The Bullseye: HST, Keck/KCWI, and Dragonfly Characterization of a Giant Nine-Ringed Galaxy. ApJL 980, L3; doi: 10.3847/2041-8213/ad9f5c
