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Jul 9, 2022

Astronomers Measure Rotation Of Most Distant Galaxy Yet

Things in the universe don’t stay at rest – they move about, they relate, they rotate. Galaxies above all boast these motions, with their revolution a vital feature in their evolution. Researchers have announced that they have calculated such rotation in the most primitive galaxy yet – the light of this object comes from about 550 million years after the Big Bang, at the very start of the Age of Galaxies.

The calculations of this galaxy – called MACS1149-JD1 – have been announced in The Astrophysical Journal Letters. Researchers used the Atacama Large Millimeter/submillimeter Array (ALMA) to calculate the redshift of the galaxy.

We live in a forever expanding universe, and the speed of light is restricted. So light takes a definite time to travel between far-away objects. As it moves, the universe expands, and the wavelengths of light from a far-away galaxy are extended, changing the light we obtain into the redder bit of the electromagnetic spectrum, thus the term "redshift".

Though, the motion has an effect on the light also. Like the Doppler shift in the sound of a siren traveling towards and away from us, when a shining object moves towards us it turns bluer, away from us it turns redder. A revolving galaxy will have a bluer side (the part that looks to come towards us), and a redder side that revolves out of sight.

With this calculation, astronomers predicted that JD1 spins at 50 kilometers (31 miles) per second; slower than the revolving speed of the Milky Way disk of 220 kilometers (136 miles) per second. Though, JD1 is much smaller than Milky Way. It has a length of only 3,000 light-years, compared to our galaxy which is 100,000 light-years long.

“The revolving speed of JD1 is much slower than those found in galaxies in afterward epochs and Milky Way and it is probable that JD1 is at an early stage of producing a rotational motion,” co-author Professor Akio Inoue, from Waseda University, told in a report.

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