Using the European Southern Observatory’s (ESO) Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, scientists have discovered the most distant galaxy ever spotted.
Named A2744_YD4, the surprisingly dusty galaxy is located in the constellation Sculptor, 13 billion light years away. That means scientists are observing it as it looked when the universe, whose age is estimated at 13.8 billion years, was just 600 million years old.
The ancient galaxy was found by astronomers via the gravitational lensing technique. Using the gravity of a group of galaxies known as Pandora’s Cluster, the researchers magnified the light of the more distant A2744_YD4.
A spectrograph on ESO’s Very Large Telescope, which determines the sizes and compositions of distant objects by analyzing the light from stars, confirmed the remote galaxy’s age.
Scientists were surprised to find a high content of dust in the galaxy along with a rapid rate of star formation.
Dust and gas come from supernova explosions produced when massive stars die. The abundance of dust in A2744_YD4 means the first massive stars formed very early in the galaxy’s history, about 200 million years before the light ALMA is observing now.
“The detection of dust in the early universe provides new information on when the first supernovae exploded, and hence, the time when the first hot stars bathed the universe in light,” the research team noted in an ESO public statement.
“Determining the timing of this ‘cosmic dawn’ is one of the holy grails of modern astronomy, and it can be indirectly probed through the study of early interstellar dust.”
There is enough dust in A2744_YD4 to create six billion Suns, and star formation is occurring 20 times faster than it is in today’s Milky Way.
Stars in the distant galaxy are being born at a rate of 20 solar masses per year.
“This rate is not unusual for such a distant galaxy, but it does shed light on how quickly the dust in A2744_YD4 formed,” noted Richard Ellis of both ESO and University College London and co-author of a paper on the findings, which will be published in The Astrophysical Journal Letters.
“Remarkably, the required time is only about 200 million years–so we are witnessing this galaxy shortly after its formation.”
ESO scientists released a video depicting the ancient galaxy for public viewing.