Cosmic dawn, when stars formed for the first time, occurred 250 million to 350 million years after the beginning of the universe, according to a new study led by researchers at University College London (UCL) and the University of Cambridge. The U.K.-led team examined six of the most distant known galaxies, whose light has taken most of the universe’s lifetime to reach us, reports Phys.org. They found that the distance of these galaxies away from Earth corresponded to a “look back” time of more than 13 billion years ago, when the universe was 550 million years old. Analysing images from the Hubble and Spitzer Space Telescopes, the researchers calculated the age of these galaxies as ranging from 200 to 300 million years, allowing an estimate of when their stars formed. Lead author Dr. Nicolas Laporte said: “Theorists speculate that the universe was a dark place for the first few hundred million years, before the first stars and galaxies formed.” The researchers analysed starlight from the galaxies as recorded by the Hubble and Spitzer, examining a marker in their energy distribution indicative of the presence of atomic hydrogen in their stellar atmospheres. This provides an estimate of the age of the stars they contain. Co-author professor Richard Ellis said: “We now eagerly await the launch of the James Webb Space Telescope (JWST), which we believe has the capability to directly witness cosmic dawn. The quest to see this important moment in the universe’s history has been a holy grail in astronomy for decades. Since we are made of material processed in stars, this is in some sense the search for our own origins.” The JWST will be the premier observatory over the next decade, serving thousands of astronomers worldwide. It consists of an infrared observatory, an immense mirror 6.5 metres wide, and a diamond-shaped sunshield.
https://phys.org/news/2021-06-cosmic-dawn-million-years-big.html
