“Teenage Galaxies” turn out to be incredibly hot

Scientists have studied “teenage galaxies” using the James Webb Telescope. We see these star systems as they were 2-3 billion years after the origin of the Universe. They turned out to be unexpectedly hot and filled with heavy elements.

The “El Gordo” cluster, which is formed by the “teenage galaxies”. Source: NASA/ESA/CSA

“Teenage Galaxies”

The farther away the galaxy is from us, the more ancient times we observe it. Most often, scientists are interested in “newborn” star systems, which we see only a few hundred million years after the origin of the Universe. But researchers from the Northwestern University of the USA and several other scientific centres were interested in “teenage galaxies”.

We see these structures as they were 2-3 billion years after the Big Bang. They are no longer so small and primitive. However, scientists have no idea how similar they are to what we see directly around us. 

This is the task that the CECILIA (Chemical Evolution Constrained using Ionized Lines in Interstellar Aurorae) sky survey is trying to solve. It is named after the outstanding astrophysicist Cecilia Payne-Gaposchkin, and the main instrument used in this case is the James Webb Space Telescope.

What scientists were trying to find out

The researchers were mainly interested in the question of why some galaxies already at such an early stage begin to fade and cease to form new stars, while others, like the Milky Way, continue to actively develop. 

Scientists believe that the key to solving this issue is to study the chemical composition and temperature of the luminaries included in these star systems. The published study is the first step towards this.

In total, scientists studied 33 “teenage galaxies” for 30 hours. Then they combined the spectra of 23 of them to understand the general state of affairs. As a result, it was found that these star systems consisted mainly of hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel.

There was nothing unusual about the first five elements. However, sulfur, argon and especially nickel are not the substances that are easily obtained in the processes occurring inside stars. This is especially true of the last element, which is mainly born in supernova explosions. Scientists still don’t know where there are so many of them in “teenage galaxies”.

But they learned that these galaxies are extremely hot. The average temperature of their stars is 13350 °C, whereas in the Milky Way, it is only 9700 °C. Scientists are also trying to find out the reasons for this.

According to phys.org

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