New observations with the Hubble Space Telescope suggest that the first galaxies and stars appeared much earlier than previously thought.
New observations with the Hubble Space Telescope suggest that the formation of the first stars and galaxies occurred when the Universe was only 500 million years old. The discovery was made by astronomers from the European Space Agency (ESA) and was presented this week during the 236th meeting of the American Astronomical Society, which is being carried out online due to the Covid-19 pandemic.
According to scientists, this first generation of stars, known as Population III, was born from the primordial matter that emerged from the Big Bang. These stars probably formed from hydrogen, helium, and lithium, the only elements that existed at the time.
ESA astronomers focused their analysis on the star cluster MACSJ0416, which formed between 500 million and 1 billion years after the Big Bang and is about 4 billion light-years from Earth. “We found no evidence of these first-generation Population III stars in this cosmic time interval,” said Rachana Bhatawdekar, the study’s leader, in a statement to the press.
With this in mind, the group developed a technique that allowed discovering galaxies with smaller masses at a distance corresponding to when the Universe was less than a billion years old. At this point in cosmic time, the lack of exotic stars and the presence of many low-mass galaxies support the hypothesis that these systems were responsible for the reionization of the Universe – and it was precisely this event that allowed Population III to emerge.
“These results have profound astrophysical consequences as they show that galaxies must have formed much earlier than we thought,” explained Bhatawdekar. “This also strongly supports the idea that low-mass/faint galaxies in the early Universe are responsible for reionization.”