The secret of a baby galaxy with a black hole, solved with magic – Hankook Ilbo VRESP

Editor’s note

Today, the universe is not an object of awe, but an object of appreciation that can be enjoyed together. The universe is full of celestial bodies that are more beautiful and amazing than the works of art created by humans and the amazing sights of nature. We plan to take you to various universes.

Graphics = Reporter Kang Jun-gu

Graphics = Reporter Kang Jun-gu

James Webb just discovered a 400 million year old galaxy
A cluster of stars containing only hydrogen and helium.
Space history filled with observations

A special academic conference was held in Iceland, an ice kingdom at 66 degrees north latitude. For a week starting on the 29th of last month, astronomers from around the world gathered to present research results on galaxies and have heated discussions. is the picture featured on the poster for this academic conference. The reason they gathered in a special place like Iceland was because the theme of the conference was a special galaxy. The author also published research results on a special galaxy that looks like a jellyfish. It was like passionately enjoying a special galaxy story in a special place. Now that I think about it, I think astronomers are really special people.

What attracted the most attention at this conference was the study of special galaxies to reveal the process by which galaxies were first born and grew after the Big Bang. Finding out the process by which galaxies were first born in the universe has been a long-standing wish of mankind, along with uncovering the process by which humans first appeared on Earth.

To find out how galaxies were first born after the Big Bang, we need to find and study the youngest galaxies. In the nearby universe, only old galaxies are visible. However, because the youngest galaxies are far away, they are very dark and difficult to find. Even if such a galaxy is found, it is difficult to investigate its characteristics. However, thanks to the James Webb Space Telescope, this difficult problem was solved. This telescope cost 13 trillion won in Korean money, but it is showing results that are more than worth the cost.

Graphics = Reporter Kang Jun-gu

Graphics = Reporter Kang Jun-gu

is a photo taken with the James Webb Telescope of a very narrow area of ​​the northern sky, and shows the appearance of deep space well. Most of the celestial bodies visible in the photo are galaxies, with only a few stars. The universe is full of galaxies. The distances of these galaxies vary greatly. Among these, the most distant galaxy (GN-z11) is in the upper right corner of the photo above. The small red dot in the upper right photo is the farthest galaxy. How can we find out the identity of such a small and dark-looking galaxy? This was not possible until the James Webb Telescope came along.

By analyzing the James Webb Telescope observation data, we learned many surprising secrets about this galaxy. The distance of this galaxy is 13.4 billion light years, making it one of the most distant galaxies known. The image shown is the light that departed from this galaxy 13.4 billion years ago, captured today by the James Webb Telescope camera. In other words, this is what the galaxy looked like 400 million years after the Big Bang began 13.8 billion years ago, so the galaxy’s age is less than 400 million years. Our Milky Way Galaxy is an old galaxy, more than 13 billion years old, making it one of the youngest baby galaxies.

The mass of this baby galaxy is a whopping 800 million times that of the Sun. Although it appears as a very small dot in the photo, it is actually a huge galaxy made up of 800 million stars. Surprisingly, there is already a very massive black hole at the center of this baby galaxy, with a mass 2 million times that of the Sun. This shows that such a massive black hole was already created in the early days of the universe. The stars around this baby galaxy are mostly composed of hydrogen and helium, with almost no heavier elements. Such stars are called Type 3 star races and have not yet been discovered.

Stars like the Sun contain a wide variety of elements, including oxygen, carbon, and nitrogen, in addition to hydrogen and helium. Hydrogen and helium were created during the Big Bang, and heavier elements are created in stars. Therefore, it is possible that the stars in this galaxy were the first stars born in the universe. Recently, galaxies farther away and younger than this galaxy have been discovered. The limits of what we can see in the universe continue to increase, getting closer and closer to the Big Bang.

In the past, the history of the universe could not be properly known, so it was described through imagination and speculation. Today, the history of the universe is written as seen through a telescope. Research on human history relies on relics and ancient documents, but research on the history of the universe relies on light (electromagnetic waves and gravitational waves) coming from celestial bodies. As telescopes and observation technologies that can see the light of celestial bodies develop, the blank spaces in the history of the universe continue to be filled. How could uncovering the history of the universe by analyzing the light coming from dark and small-looking galaxies not be called magic?

Myung-Kyun Lee, Professor Emeritus, Department of Physics and Astronomy, Seoul National University

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Myungkyun LeeProfessor Emeritus, Department of Physics and Astronomy, Seoul National University