Astronomers Study Ancient Stardust to Understand First Stars

This image is dominated by a spectacular view of the rich galaxy cluster Abell 2744 from the NASA/ESA Hubble Space Telescope. But, far beyond this cluster, and seen when the Universe was only about 600 million years old, is a very faint galaxy called A2744_YD4. New observations of this galaxy with ALMA, shown in red, have demonstrated that it is rich in dust.

An international team of astronomers is excited with the surprise from the paradox flowing from a young galaxy that is full of stardust from the early universe. The study of the new galaxy is giving them vital leads on the formation of the first stars in the universe.

The dust-filled galaxy with the name A2744_YD4 is the youngest yet the most remote galaxy ever spotted.

Led by Nicolas Laporte of University College London, the team observed the galaxy from Chile’s European Southern Observatory’s Atacama Large Millimeter/submillimeter Array.

Veiled By Pandora’s Cluster

The telescopic observations gave the team an idea that the distance of A2744_YD4 from Earth is around 13 billion light-years. 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.

The unique galaxy’s detection was enabled by a process called gravitational lensing, which is facilitated by the gravity exerted from the vicinity of Pandora’s Cluster helping astronomers to see A2744_YD4 with a bigger magnification of light.

In calculating the distance of A2744_YD4, the astronomers also made use of ESO’s Very Large Telescope and X-shooter as the spectrograph. They also noticed emissions of ionized oxygen from the ALMA observations.

For the astronomers, the new galaxy offered the view when the universe was in the infancy of 600 million years. That was the period when early stars and galaxies were formed. Remember, the current age of the universe is close to 14 billion years.

Heavy Volumes Of Stardust

In supernova explosions, the death of stars happens and vestiges of dust and gas get splattered, which later turn into raw material for forming new stars and celestial bodies.

The astronomers were considerably surprised over the heavy load of star remnants present in the youngest galaxy detected. This is despite the fact that the earliest universe has the least probability of having its first-generation stars die out to leave behind stardust in such high quantities.

Commenting on the heavy amount of stardust remnants found in the distant galaxy, the lead researcher underscored that the material has come from supernovae event only and it drastically polluted the galaxy with dust and gas.

“Not only is A2744_YD4 the most distant galaxy yet observed by ALMA, but the detection of so much dust indicates [that] early supernovae must have already polluted this galaxy,” said Nicolas Laporte, the lead researcher from the University College in London.

Holy Grails Of Astronomy

The young galaxy’s stardust is a valuable clue for the researchers and serves as a treasure trove of information in studying the time frame and period of the first supernovae and the time when stars lit up the whole universe.

“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,” ESO said.

Massive Stardust

According to ESO, the volume of stardust contained in A2744_YD4 can form 6 million suns. Also, the birth of little stars in A2744_YD4 has been rapid, happening at the rate of 20 solar masses a year, or almost 20 times more than the star formation in the Milky Way.

This finally leads to the conclusion that A2744_YD4 must be carrying the oldest stardust of the early stars of the universe.


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