Astronomers, using the James Webb Space Telescope (JWST), have identified a massive and distant spiral galaxy, named Zhúlóng, as reported by phys.org. With a redshift of approximately 5.2, this discovery places the galaxy in a time when the universe was less than a billion years old. Zhúlóng, characterized by its grand-design spiral structure, exhibits an expansive stellar disk and a quiescent core, marking a significant milestone in understanding the evolution of galaxies. This breakthrough highlights the early formation of mature galactic structures.

Zhúlóng: Insights from the JWST PANORAMIC Survey

According to the study published on December 17 on the pre-print platform arXiv, conducted by Mengyuan Xiao and a team from the University of Geneva, Zhúlóng was detected in the JWST’s PANORAMIC survey. The galaxy, named after a mythical red solar dragon in Chinese lore, was found to have a stellar mass comparable to the Milky Way. Spanning 62,000 light-years, its spiral arms form a well-defined grand-design structure. The quiescent core, observed as red and densely packed, contrasts with the star-forming outer disk, indicating a transformation phase from active star formation to quiescence.

Characteristics of the Galaxy

Zhúlóng’s star-formation rate was estimated at 66 solar masses per year, considered moderate for a galaxy of its size and epoch, as per reports. The conversion efficiency of baryons to stars in this galaxy was calculated to be approximately 0.3, surpassing that of many later-formed galaxies. These findings suggest that Zhúlóng underwent efficient star formation in its early stages.

Implications for Galactic Evolution

The discovery underscores the emergence of mature galactic structures much earlier than previously assumed. Zhúlóng, described as the most distant spiral galaxy identified to date, offers valuable insights into the processes of galaxy formation and evolution in the early universe.