Astronomers have found a rare cosmic phenomenon: a giant galaxy featuring nine concentric rings, making it unique among known galaxies. The galaxy, officially named LEDA 1313424 and nicknamed the Bullseye Galaxy, lies approximately 567 million light-years away in the constellation Pisces. This discovery was recently published in The Astrophysical Journal Letters on February 4, confirming the existence of the galaxy with the most ring structures ever observed.
About 50 million years ago, a smaller blue dwarf galaxy plunged through the core of the Bullseye Galaxy, an event likened to a dart piercing the center of a target. This collision created ripples that expanded outward, forming nine symmetrical, star-filled rings. Such an event is extremely rare, as it is uncommon for one galaxy to dive through the center of another.
"This was a serendipitous discovery," said Imad Pasha, a PhD student at Yale University and lead author of the study, according to NASA Science. "I was looking at ground-based imaging and when I saw a galaxy with several clear rings, I was immediately fascinated and had to stop to investigate it."
The collision not only left behind the concentric rings but also ignited regions of new star formation as gas was ejected outward during the passage of the blue dwarf galaxy. Each ring in the Bullseye Galaxy facilitates new star creation as gases and dust intermingle, creating a display resembling ripples formed when a stone breaks the surface of a tranquil pond.
"We're catching the Bullseye at a very special moment in time," remarked Yale Professor Pieter G. van Dokkum, co-author of the study, as reported by Space.com. He noted the narrow window after the impact when a galaxy like this would have so many rings. "That theory was developed for the day that someone saw so many rings. It is immensely gratifying to confirm this long-standing prediction with the Bullseye Galaxy," he added.
High-resolution imagery from NASA's Hubble Space Telescope confirmed eight rings around the Bullseye Galaxy. An additional ninth ring was confirmed using data from the W. M. Keck Observatory in Hawaii, as noted by scienceblog.com. The observations align remarkably well with theoretical predictions of ring formation, confirming models developed decades ago.
The Bullseye Galaxy spans approximately 250,000 light-years across, making it two and a half times the size of our Milky Way, which is about 100,000 light-years in diameter. The blue dwarf galaxy that passed through it is now located about 130,000 light-years away from the Bullseye, connected by a tenuous strand of gas and dust.
Astronomers believe that the first two rings in the Bullseye formed rapidly as the blue dwarf galaxy took its plunge, with subsequent rings appearing in a more staggered manner. The outer rings are more spaced out than the inner ones, suggesting the galaxy's dynamic evolution after the collision.
"This galaxy breaks the record for most rings discovered in this type of system," Pasha said. "It is a confluence of catching it at a lucky time, at a lucky orientation, and arising from a lucky collision configuration."
Looking ahead, the researchers are eager to determine which stars existed in the Bullseye Galaxy before and after the collision. They plan to improve models showing how the galaxy may continue to evolve over billions of years. The upcoming Nancy Grace Roman Space Telescope promises to enhance the ability to study such cosmic phenomena. "Once NASA's Nancy Grace Roman Space Telescope begins science operations, interesting objects will pop out much more easily," van Dokkum stated. "We will learn how rare these spectacular events really are."
The article was written with the assistance of a news analysis system.