An international team of astronomers recently made a major discovery using the James Webb Space Telescope (JWST). They identified a giant (grand-design) spiral galaxy, named Zhúlóng, which may well be the most distant ever observed.
This galaxy, located at a photometric redshift of approximately 5.2, has a mass comparable to that of the Milky Way. Zhúlóng is distinguished by its well-defined spiral arms, spanning 62,000 light years, and a classical core. This discovery, published in arXivopens new perspectives on the formation of galaxies in the young Universe.
Spectral analyzes reveal that Zhúlóng’s core is in a quiescent phase, while its disk continues to form stars. This configuration suggests growth of the galaxy from the inside out, a process still poorly understood in the first billion years of the Universe.
Zhúlóng’s star formation rate is relatively low, estimated at 66 solar masses per year. However, the conversion efficiency from baryons to stars is remarkably high, indicating a transitional phase between an active and a quiescent galaxy.
This discovery raises questions about how quickly mature galaxies were able to form after the Big Bang. Zhúlóng, with its unique characteristics, provides a valuable window into the processes of galaxy formation and evolution in the young Universe.
The researchers, led by Mengyuan Xiao of the University of Geneva, continue to analyze the data to better understand the mechanisms at work in this distant galaxy. Their work could well shake up our understanding of the primordial Universe.
-What is a grand-design spiral galaxy?
Grand-design spiral galaxies are characterized by their well-defined and symmetrical spiral arms, which extend from a clear central core. These arms are regions of density high where star formation is activated by the compression of the matter.
These galaxies are relatively rare in the young Universe, which makes Zhúlóng’s discovery particularly significant. Astronomers believe that grand-design spiral galaxies represent an important step in the evolution of galaxies.
The spiral structure is often associated with complex internal dynamics, influenced by gravitational interactions and density waves. These processes play a crucial role in the formation and evolution of galaxies.
How do we measure the red shift of galaxies?
Redshift, or redshift, is a key measurement in astronomy to determine the distance and age of galaxies. It is calculated by observing the stretching of the wavelengths of the light emitted by celestial objects. For Zhúlóng, the photometric redshift was estimated at around 5.2, which corresponds to a time when the Universe was less than a billion years old. This measurement is crucial for understanding the evolution of galaxies in the young Universe.
Spectroscopy and photometry techniques are used to measure redshift accurately. These methods allow astronomers to reconstruct the history of the Universe and to better understand the processes of galaxy formation.
