Astronomers Spot Ancient Stardust From the First Ever Stars in the Universe
Astronomers from the European Southern Observatory (ESO) have glimpsed a distant young galaxy with plenty of ancient stardust from the earliest stars that ever came to life.
According to a report from ESO, the galaxy -- named A2744_YD4 -- was the youngest and the most remote ever seen by the Atacama Large Millimeter/submillimeter Array (ALMA). An international team led by Nicolas Laporte of the University College of London spearheaded the search, then used ESO's Very Large Telescope to follow up and confirm the distance of A2744_YD4.
This galaxy is 13 billion light-years away from Earth, appearing to the astronomers as it was when the Universe was only 600 million years old, only 4 percent of its present age of 13.82 billion years. At A2744_YD4's point in the Universe's existence, the first stars and galaxies were only just forming.
The discovery marks the most distant -- and thus, earliest -- cosmic dust and oxygen ever detected.
Cosmic dust is particularly significant, as it is scattered in space in the wake of supernova explosions - when stars die. Its presence in the early Universe provide new data on when the first supernovae explosions occurred and when the first hot stars lit up the Universe. This timeline is one of the great mysteries of modern astronomy, and observing the stardust from the early Universe could be the key in solving the puzzle.
"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," Laporte explained.
The scientists determined that the dust scattered in A2744_YD4 added up to about six million times the mass of the Sun, while the mass of all its stars amounted to two billion times the mass of the Sun. Stars here formed at a rate of 20 solar masses per year, a far cry from the Milky Way's rate of one solar mass per year.
With this data, the team was able to estimate how long it takes for the dust that ALMA detected to form.
"Remarkably, the required time is only about 200 million years - so we are witnessing this galaxy shortly after its formation," study co-author Richard Ellis said.
The stars from which the dust were created began forming 200 million years before the light from A2744_YD4 reached Earth, which means these are some of the vestiges of the earliest stars in the Universe.