The James Webb Space Telescope has identified the most distant ring galaxy ever observed. This galaxy, named GS18660, represents a view that existed approximately 2.1 billion years after the Big Bang and is presumed to have formed as a result of two galaxies colliding in the early Universe.
The structure attracts attention due to the presence of a ring of newborn stars. According to a study published on September 8th in the journal Astronomy & Astrophysics, various pieces of evidence suggest that a smaller galaxy might have passed through the center of GS18660, triggering the formation of this ring.
However, this hypothesis has not been definitively confirmed. Researchers consider a collision the most likely explanation but acknowledge the need to study other possible scenarios.
GS18660 was selected for observation because previous images from the Hubble Space Telescope showed an elongated structure. Initially, researchers were not specifically looking for a ring galaxy.
It was only through more detailed observations by James Webb using the NIRSpec instrument that the circular structure became apparent. Scientists were able to study the galaxy's shape in three dimensions, track the movement of hot gas, analyze its chemical composition, and investigate its star formation history.
The data obtained also helped estimate the time of the presumed collision. According to the team's calculations, this event could have occurred between 17 and 42 million years before the observed period.
Researchers also believe that between 10% and 20% of the stellar mass in the ring region formed in the last tens of millions of years. This strengthens the probability that the impact triggered an intense episode of star formation.
The interpretation is based on a combination of the galaxy's characteristics, including the ring, the presence of a satellite, and a gas bridge between the objects. Another possible reason is that an internal structure, resembling a stellar bridge, could have directed gas and stars into specific areas, forming the ring without the involvement of an external galaxy.
GS18660 itself possesses a bridge-like structure extending from north to south. It is currently unclear whether this is a real stellar structure or also a result of galactic interaction.
This discovery may also help astronomers understand the frequency of such structures in the past. Previous estimates suggested that collision-formed ring galaxies were as rare in the early Universe as they are now, appearing roughly one in ten thousand galaxies.
If the origin of GS18660 is confirmed as a collision, this estimate may need revision, indicating that such an event was more common in the early stages of cosmic history.
Regardless of the final explanation, this object provides an opportunity to study how galaxies developed complex structures when the Universe was only a few billion years old.
