In images taken by the James Webb Space Telescope, scientists discovered a small galaxy from the young Universe, only 1.4 billion years old. Despite this, the galaxy, to the surprise of astronomers, contains several generations of stars and many chemical elements, and the metallicity of some of its stars is comparable to that of the Sun.
Astronomers from Cornell University (USA) were studying images of the known early galaxy SPT0418-47, taken with NASA's James Webb Space Telescope (JWST), when their attention was drawn to a bright object near the outer edge of the galaxy. Further investigation revealed that it is a small companion galaxy, which, oddly enough, contains several generations of stars, although its age does not exceed 1.4 billion years.
In addition, this young galaxy was abundant in various chemical elements. The results of the study, published in the Astrophysical Journal Letters, could change the understanding of the formation of stars and galaxies of the early Universe.
The unique galaxy was named SPT0418-SE, and it is located very close to its companion SPT0418-47. Therefore, they could probably interact and perhaps even merge with each other. This observation adds to the understanding of how early galaxies may have evolved into larger galaxies.
SPT0418-SE and SPT0418-47 have small masses compared to other galaxies in the early universe.
However, the most surprising feature of the discovered galaxy was its mature metallicity, surprising for such age and mass. Metallicity is the relative concentration of elements heavier than hydrogen and helium, such as carbon, oxygen and nitrogen.
Scientists estimate that the metallicity of some SPT0418-SE stars is comparable to that of the Sun, which is over four billion years old. Our sun inherited most of its metals from previous generations of stars, which took billions of years to create them.
In SPT0418-SE, scientists have observed traces of at least several generations of stars that managed to appear and die during the first billion years of the universe. It is likely that the star formation process in this galaxy must have been efficient and started very early.