Dust-filled galaxy from very early universe discovered

Dust-filled galaxy from very early universe discovered
 For the first time, astronomers have discovered a dust-filled galaxy from the very early universe. Dust plays an extremely important role in the universe - both in the formation of planets and new stars. But scientists believe that dust was not there from the beginning and the earliest galaxies had no dust, only gas.

The new research demonstrates that galaxies were very quickly enriched with dust particles containing elements such as carbon and oxygen, which could form planets.
The dust is comprised primarily of elements such as carbon, silicon, magnesium, iron and oxygen. The elements are synthesised by the nuclear combustion process in stars and driven out into space when the star dies and explodes.

In space, they gather in clouds of dust and gas, which form new stars, and for each generation of new stars, more elements are formed. This is a slow process and in the very earliest galaxies, dust had not yet formed.

Now, researchers have discovered a very distant galaxy that contains a large amount of dust, changing astronomers' previous calculations of how quickly the dust was formed.

"It is the first time dust has been discovered in one of the most distant galaxies ever observed - only 700 million years after the Big Bang," said Darach Watson, an astrophysicist with the Dark Cosmology Centre at the Niels Bohr Institute at the University of Copenhagen.

"It is a galaxy of modest size and yet it is already full of dust. This is very surprising and it tells us that ordinary galaxies were enriched with heavier elements far faster than expected," Watson said.

"We looked for the most distant galaxies in the universe. Based on the colours of the light observed with the Hubble Space Telescope we can see which galaxies could be very distant," said Lise Christensen, an astrophysicist at the Dark Cosmology Centre at the Niels Bohr Institute.

"Using observations from the very sensitive instrument, the X-shooter spectrograph on the Large Telescope, VLT in Chile, we measured the galaxy's spectrum and from that calculated its redshift, ie the change in the light's wavelength as the object recedes from us.

"From the redshift we can calculate the galaxy's distance from us and it turned out to be, as we suspected, one of the most distant galaxies we know of to date," Christensen said.

Watson said that they then studied the galaxy with the ALMA telescopes and found that the galaxy was full of dust.

He explained that young stars in early galaxies emit hot ultraviolet light. The hot ultraviolet radiation heats the surrounding ice-cold dust, which then emits light in the far-infrared.

"It is this far-infrared light, which tells us that there is dust in the galaxy. It is very surprising and it is the first time that dust has been found in such an early galaxy," said Watson.

"The process of star formation must therefore have started very early in the history of the universe and be associated with the formation of dust," Watson said.
The results are published in the scientific journal Nature.
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