Ancient stardust sheds light on the first stars
A huge mass of glowing stardust in a galaxy seen shortly after the Universe's formation has been detected by a UCL-led team of astronomers, providing new insights into the birth and explosive deaths of the very first stars. The galaxy is the most distant object ever observed by the Atacama Large Millimeter/submillimeter Array (ALMA) and was seen when the Universe was only four percent of its present age, at about 600 million years old, when the first stars and galaxies were forming. It is also the most distant galaxy in which dust and oxygen has been detected. The study, funded by the European Research Council and published today in The Astrophysical Journal Letters , observed A2744_YD4, the youngest and most remote galaxy ever seen using ALMA. The team, led by Dr Nicolas Laporte (UCL Physics & Astronomy), was surprised to find that this youthful galaxy, whose enormous distance was confirmed with the X-Shooter instrument on ESO's Very Large Telescope, contained an abundance of interstellar dust formed by the deaths of an earlier generation of stars. Study lead, Dr Nicolas Laporte, said: 'Not only is A2744_YD4 the most distant galaxy yet observed by ALMA, but the detection of so much dust indicates early supernovae must have already polluted this galaxy.' Cosmic dust is mainly composed of silicon, carbon and aluminium, in grains as small as a millionth of a centimetre across. The chemical elements in these grains are forged inside stars and are scattered across the cosmos when the stars die, most spectacularly in supernova explosions, the final fate of short-lived, massive stars.
