Oldest Known Spiral Galaxy Seen With Pond-Like Ripples in Astronomical First
Astronomers have detected pond-like ripples across the gaseous disk of an ancient galaxy, providing insights into its formation and star formation activity.
The Ancient Spiral Galaxy BRI 1335-0417
Astronomers have discovered pond-like ripples in the gaseous disk of the oldest known spiral galaxy, BRI 1335-0417. This galaxy, which is over 12 billion years old, offers valuable insights into the formation and evolution of galaxies. The ripples in the disk reveal the galaxy's growth patterns and could help explain its rapid star formation rate. BRI 1335-0417 forms stars much more prolifically than modern galaxies like the Milky Way.
The observations were made using the Atacama Large Millimetre/submillimetre Array (ALMA), which is highly effective at observing gas and dust. These ripples provide evidence of an external influence on the galaxy, such as interactions with another galaxy or incoming gas. These influences can trigger rapid star formation and contribute to BRI 1335-0417's efficient star-forming process.
Discovering the Barred Spiral Galaxy
ALMA's observations also revealed evidence of a central bar in BRI 1335-0417. Bars in spiral galaxies can channel gas from the arms into the galaxy's central region, fueling star formation and potentially explaining the presence of active galactic nuclei. The bar identified in the gas-rich disk galaxy is approximately 3.3 kiloparsecs long and drives the rapid evolution of the galaxy. This discovery challenges the belief that bars form later in a galaxy's evolution, suggesting a new mechanism for early bar formation.
Finding a bar in a galaxy that is so ancient provides new insights into the early stages of galaxy formation. The prevalence of bar-like structures seen in high-redshift submillimeter galaxies can potentially be explained by the gravitationally unstable gas-rich disk creating a star-forming gaseous bar.
Unraveling Galaxy Formation and Evolution
The detection of pond-like ripples and a central bar in the ancient spiral galaxy BRI 1335-0417 challenges established theories on galaxy formation and evolution. It suggests that interactions with other galaxies or massive gas clouds can significantly impact a galaxy's star formation activity and growth patterns.
While the concept of galaxies evolving through mergers and interactions is not challenged by these findings, they provide astronomers with a deeper understanding of the intricate processes involved. The observations of ripples and bars offer valuable insights into the mechanisms behind galaxy formation and evolution.
