Ancient Stardust Sheds Light On First Stars In Universe

Stardust is very common in our part of the universe, but was very rare for the first billion years of the universe's history. Such dust was produced by an earlier generation of stars and these observations provide insights into the birth and explosive deaths of the very first stars in the Universe.

Astronomers used the ALMA telescope in Chile to observe the galaxy A2744_YD4. This was around the same time that the first stars and galaxies were formed. For the analysis, they used two telescopes in northern Chile, the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope (VLT). An worldwide 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. The galaxy, A2744_YD4, is one of the farthest galaxies ever spotted, and studying this young galaxy could help astronomers discover how the first stars lived and died. "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 said.

This image is dominated by a spectacular view of the rich galaxy cluster Abell 2744 from the NASA/ESA Hubble Space Telescope.

The galaxy took only about 200 million years to reach its observed form, explained one of the paper's co-authors, Professor Richard Ellis, in a University College-London statement, "so we are witnessing this galaxy shortly after its formation". But in the early 2010s, the completion of ALMA's 66 radio antennas gave scientists a powerful new tool to study these dust clouds. Image credit: ALMA / ESO / NAOJ / NRAO / NASA / ESA / D. Coe, STScI / J. Merten, Heidelberg & Bologna. Stardust is formed by dying stars, particularly by exploding supernovas, and contains heavier elements like carbon, silicon, and aluminum that are crucial for the creation of complex molecules and life.

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Reportedly the observation of A2744_YD4 was made possible because it lies behind a massive cluster of galaxies called as Abell 2744.

They also noticed emissions of ionized oxygen from the ALMA observations.

The discovery marks the most distant - and thus, earliest - cosmic dust and oxygen ever detected. 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.

Galaxy A2744_YD4 appears to hold enough of this stardust to make 6 million suns, while the mass of the galaxy's stars add up to 2 billion times the mass of the sun. A2744_YD4 produces stars at a rate of 20 solar masses per year, which is a full 20 times the rate of our Milky Way's comparatively paltry star formation rate of 1 solar mass per year. Far beyond this cluster is the faint, young galaxy A2744_YD4. Based upon this rate, the group estimated that only about 200 million years were needed to form the dust seen in A2744_YD4.

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