Cosmic stardust from the dawn of the universe detected by Alma telescope
This discovery gives new insights regarding the birth and deaths of the very first stars ever to be seen. Scientists estimate that the universe is about 13.8 billion years old, so light from A2744_YD4 has spent just about an eternity traveling to the ALMA telescope array. The ALMA observations are also the most distant detection of oxygen in the Universe. That was the period when early stars and galaxies were formed. Galaxy A2744_YD4 is the farthest galaxy ever observed by astronomers. Because stardust is formed from exploding stars, finding it in such a young galaxy is surprising.
In calculating the distance of A2744_YD4, the astronomers also made use of ESO's Very Large Telescope and X-shooter as the spectrograph.
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.
"Further measurements of this kind offer the exciting prospect of tracing early star formation and the creation of the heavier chemical elements even further back into the early Universe", study lead author Nicolas Laporte from the University College London said in the statement. According to the study by the astronomers, the newly found galaxy is part of Sculptor constellation and is overshadowed by Pandora's Cluster, a batch of galaxies. After 400 million years, the atoms were able to clump into stars, whose nuclear fusion allowed the universe to switch back on.
ALMA observations have uncovered an extremely young, dusty galaxy already polluted with the products of supernovae, as pictured in this artist's impression. Image credit: ALMA / ESO / NAOJ / NRAO / NASA / ESA / D. Coe, STScI / J. Merten, Heidelberg & Bologna.
The tiny grains are scattered across space when a star dies in a supernova explosion.
Stardust is the leftovers from star explosions, or supernovae, when the star has reached the end of its life.
It was through observations of the surprisingly large amounts of such interstellar dust in A2744_YD4 that the team detected the glowing emission of ionised oxygen.
The ALMA telescopes also revealed the presence of ionized oxygen in the galaxy, making it the farthest -and thus the earliest - sources of the gas in the universe.
The European Southern Observatory, which operates the ALMA telescope, said: "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". 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. In comparison, the rate of star formation in the Milky Way is just one solar mass per year. "Remarkably, the required time is only about 200 million years - so we are witnessing this galaxy shortly after its formation".
This means that significant star formation began approximately 200 million years before the epoch at which the galaxy is being observed. This dust is an integral component of today's stars (like our Sun) and the planets surrounding them.