He James Webb Space Telescope continues to impress the world with His new discoveries. This time, it has found five very old star clusters, the first ever observed in a young galaxy, just 500 million years after the Big Bang.
This discovery, crucial for reconstructing the evolution of galaxies in the early universe, has been published in the journal Nature by an international team led by the Italian astronomer Angela Adamo from Stockholm University. Contributors include Eros Vanzella and Matteo Messa from the National Institute of Astrophysics in Bologna.
Observing distant galaxies
The young galaxies of the early universe are a rich source of informationsince they hosted intense phases of star formation that generated large amounts of ionizing radiation, making the universe more transparent (in the so-called era of reionization).
Observing these distant galaxies is a challengebut fortunately, the universe itself helps us through “gravitational lenses.” These are distributions of matter so dense that they bend space-time and deflect the path of light rays, amplifying the light coming from the most distant galaxies.
Thanks to this effect, a very young galaxy called the Cosmic Gem Arc was discovered, which we see as it was only 460 million years after the Big Bang.
First observed by the Hubble Space Telescope in 2018now shown in great detail by its “heir”, the James Webb (JWST), managed by the space agencies of Europe (ESA), the United States (NASA) and Canada (CSA).
Cosmic jewels in a young galaxy
Never before have the internal properties of such a distant galaxy been observed. The researchers managed to identify five star clusters, each with a size of approximately 3-4 light years. This indicates that these are very dense clusters, a thousand times larger than typical young star clusters observed in the local universe.
“The surprise and amazement was incredible when we opened the Webb images for the first time,” said Angela Adamo. “We saw a little chain of bright points, reflected side to side – these cosmic gems are star clusters! Without Webb, we wouldn’t have known we were observing star clusters in such a young galaxy.”
Implications of the discovery
The presence of such dense and massive star clusters is important for two reasons:
- They could be the precursors of the globular clusters that populate today's galaxies.
- During their formation, these young star clusters can “destroy” the interstellar medium of the host galaxy and, with their young, massive stars, play a crucial role in the process of reionization of the universe.
“We are finally uncovering the origins of the first galaxies with the quality and power of the JWST telescope, and thanks to gravitational lensing, we are seeing unprecedented detail,” Vanzella added. “The universe back then was not like the universe of today, and now this seems a fact to us.”
This discovery represents a major step forward in our understanding of the first galaxies and the process of reionization of the universe. The James Webb telescope continues to amaze us with its new observations and promises to reveal even more secrets of the cosmos in the coming years.