In a Galaxy Far, Far Away, Scientists Find Oldest Known Stardust

This artist’s impression shows what the very distant young galaxy A2744_YD4 seen when the Universe was just 4% of its current age might look like. Image ESO  M. Kornmesser

Cosmic stardust from the dawn of the universe detected by Alma telescope

Stardust is very common in our part of the universe, but was very rare for the first billion years of the universe's history. By using Gravitational lensing technique, the young galaxy could be observed clearly with about 1.8 times magnification. The ALMA observations are also the most distant detection of oxygen in the Universe. The presence of oxygen in this distant galaxy gives us a hint to when and how the first galaxies formed and what caused the cosmic "reionization". For the analysis, they used two telescopes in northern Chile, the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope (VLT).

"The galaxy appears to us as it was when the Universe was only 600 million years old, during the period when the first stars and galaxies were forming", said the European Southern Observatory, which operates the VLT and is one of the partners in ALMA, in a press release. Findings indicate stars started to form when just 400 million years after the dawn of the universe.

ALMA (ESO/NAOJ/NRAO), NASA, ESA, ESO and D. Coe (STScI)/J.

The tiny grains are scattered across space when a star dies in a supernova explosion.

Nearly all of the elements around us today - from the oxygen in the atmosphere to the nitrogen in human DNA to the uranium in power plants - were forged within stars and then scattered by supernovae before clumping into other stars, planets, and, ultimately, human beings. The newly discovered dust is said to be plentiful and has since become a key building block in star formation in the early universe.

All of this was made possible by the fact that A2744_YD4 sits behind a massive galaxy cluster called Abell 2744, also known as Pandora's Cluster. However, at the start of the universe it was very scarce - there had not been enough time for many stars to have died.

Further to this, the team also detected ionised oxygen coming from the galaxy - making it the earliest oxygen ever detected.

The dust-filled galaxy with the name A2744_YD4 is the youngest yet the most remote galaxy ever spotted. Located about 13 billion light-years away, it's filled with dust from exploded stars - and according to scientists, the dust could be the remnants of the first stars in the Universe.

The galaxy is estimated to contain an amount of dust equivalent to six million times the mass of our sun. In comparison, the rate of star formation in the Milky Way is just one solar mass per year.

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.

This provides a great opportunity for ALMA to help study the era when the first stars and galaxies "switched on" - the earliest epoch yet probed. This dust is an integral component of today's stars (like our Sun) and the planets surrounding them. Says Laporte, "Further measurements of this kind offer the exciting prospect of tracing early star formation even further back into the early universe".

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