Researchers have identified a large, well-structured spiral galaxy named Alaknanda, located approximately 12 billion light-years from Earth. This discovery, made using NASA’s James Webb Space Telescope, reveals a galaxy that formed shortly after the Big Bang, when the universe was only about 1.5 billion years old. The observations were part of extensive sky surveys that have only recently become possible due to advancements in telescope technology.
Historically, astronomers believed that galaxies in the early universe were too chaotic to develop into organized spiral shapes. The prevailing theory suggested that young stars and gas moved in a tumultuous manner, resulting in irregular clumps instead of the smooth disks and arms characteristic of spiral galaxies. This view was largely supported by previous observations from the Hubble Space Telescope, which showed that spiral galaxies were rare in the early universe, particularly beyond 11 billion years in look-back time.
The discovery of Alaknanda challenges these established notions. “Alaknanda reveals that the early universe was capable of far more rapid galaxy assembly than we anticipated,” said Yogesh Wadadekar, co-author of the study. “Somehow, this galaxy managed to pull together 10 billion solar masses of stars and organise them into a beautiful spiral disk in just a few hundred million years. That’s extraordinarily fast by cosmic standards, and it compels astronomers to rethink how galaxies form.”
Significance of Alaknanda’s Structure
The emergence of Alaknanda adds to a growing list of disk-shaped galaxies observed by the James Webb Space Telescope, including two spiral galaxies discovered in 2023 and 2024: CEERS-2112 and REBELS-25. The research team from the Tata Institute of Fundamental Research in India published their findings in the journal Astronomy & Astrophysics. Through a natural phenomenon known as gravitational lensing, astronomers were able to observe Alaknanda in remarkable detail. The gravity of a massive galaxy cluster acts like a cosmic magnifying glass, enhancing the light from Alaknanda to appear twice as bright.
The images captured reveal that Alaknanda spans roughly 32,000 light-years across, comparable to large modern spiral galaxies. It boasts a flat, rotating disk with two smooth, symmetrical spiral arms, earning it the designation of a “grand-design” spiral galaxy. This classification indicates that its arms are well-defined, rather than patchy or fragmented. Along these arms, researchers have observed chains of bright clumps of newborn stars, resembling strings of beads, which signify areas where gas has collapsed into dense pockets that ignite new star formation.
By analyzing Alaknanda across 21 different wavelengths of light, spanning ultraviolet to infrared, scientists estimated that the galaxy’s stars have an average age of only 200 million years. This finding indicates that nearly half of the galaxy’s stars formed in a rapid burst after the universe had already reached the age of over 1 billion years.
Future Research Directions
Alaknanda continues to experience rapid growth, forming new stars at a rate equivalent to about 63 suns per year, significantly faster than the Milky Way’s current rate. Certain wavelengths shine brighter than anticipated, indicating intense star-forming activity driven by the glowing gas around new stars.
Despite these insights, many questions remain regarding how spiral arms developed so swiftly in such ancient galaxies. Some theories propose that these structures arise from slow-moving density patterns within the disks, while others suggest gravitational interactions from nearby galaxies or large gas clumps. Preliminary observations indicate that Alaknanda may have a small neighboring galaxy, which could have influenced its spiral structure, but further evidence is necessary to confirm this hypothesis.
Future observations with Webb’s instruments, along with data from radio telescopes, could provide deeper insights into the motions of stars and gas within Alaknanda. This research may ultimately reveal whether the galaxy’s disk has reached its final configuration or if the spiral arms represent a transitional phase in its evolution, thereby enhancing our understanding of galaxy formation in the early universe.
