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The most distant galaxy is subverting our model of the history of the universe



Looking into the universe with a telescope means going back in time, because the speed of light is so slow that even the light from nearby stars in our galaxy takes years or thousands of years to reach us. In this way, very distant galaxies also allow humans to peek into the past of the universe, which is why the most distant galaxies and the oldest galaxies have been discovered.

According to a new study Released on December 14 In the “Natural Astronomy” magazine, astronomers have confirmed the most distant galaxy in our universe. This galaxy is called GN-z11. It is so far away that it forms the boundary of the universe 13.4 billion light-years away from the earth, which means that the light we see from it was 1

3.4 billion years ago. It stayed—only 400 million years after the Big Bang.

The co-author of the study, Nobunari Kashikawa of the Faculty of Science at the University of Tokyo explained to Salon that the current designation of GN-z11 as the “oldest” galaxy may be short because the telescope constantly scans the sky.

Kashikawa wrote via e-mail: “GN-z11 is the most distant galaxy we know today. Maybe tomorrow we will discover more distant galaxies.”

Although the distant galaxy was originally discovered by the Hubble Space Telescope in 2016, Kashkavac and his team used the Keck 1 telescope in Hawaii to confirm its age and distance. Kachuan explained that when it was discovered, astronomers estimated that it was 13.4 billion light-years away. This was based on the discovery of a break called the “Lyman Break”, which was called the “spectrum of distant galaxies.” feature”. .

Attempting to discover such a distant, faint galaxy pushed the Hubble Space Telescope to its technological limit.

The author of the 2016 study, Gabriel Brammer (Gabriel Brammer) said in an article: “Our spectral observations show that the Milky Way is farther than we originally thought, just at the distance limit observed by Hubble. Place.” statement.

Astronomers measure its distance by determining its redshift, which is a measurement of its speed from the earth. As the universe is expanding, all objects in the sky that are not bound by gravity to our own Milky Way are retreating from the earth.When they do, these objects The light extends to longer wavelengths and therefore turns red. The farther the Milky Way, the greater the redshift.

In order to determine the distance between GN-z11 and the Earth, Kashikawa’s team studied its spectral characteristics, because observations made by the Hubble Space Telescope are very limited.

“Even Hubble can’t solve the ultraviolet emission line we need,” Baichuan said statement. “So we turned to the latest terrestrial spectrometer, which is an instrument used to measure emission lines, called MOSFIRE, installed in Keck One Telescope in Hawaii. “

Kashikawa told Sharon that it is difficult to determine whether the spectrum is actually interrupted. Specifically, the research team turned to ultraviolet light to discover the chemical characteristics of redshift. The bottom line is to have the right equipment to confirm and identify spectral breaks.

Kashikawa told Sharon via email: “Because the wavelength cannot be accurately measured, the accuracy of the distance to the Milky Way is uncertain.” “Once we believe that the carbon and oxygen emission lines we detected this time are real, then calculate them. The distance between them will not be so difficult.”

Even if this galaxy is far away, astronomers hope it has information that we can understand our own galaxy and the universe.

Ashikawa told Sharon: “The detected light of carbon and oxygen suggests special physical conditions that are not in today’s galaxies.” “The age of GN-z11 is estimated to be only 70 million years, and its mass is estimated to be ten times that of the sun (a component of stars). Billion times, this shows that this young galaxy was born and grew rapidly.”

Baichuan said: “The fact that carbon and oxygen were found in GN-z11 shows that this galaxy is not the first (metal-free) galaxy in the universe.” Because elements heavier than hydrogen and helium are only found in massive stars Forgery, so the presence of heavy elements such as carbon indicates that the stars in the Milky Way are at least the second generation, which means that a generation of the great sun has already existed and died, expelling its metal into the Milky Way.

Ashikawa said this means that the first galaxy in the universe is still “in a farther universe that humans don’t know.”

Next year will be an important year for astronomy, especially in terms of how we can better understand the universe.

Ashikawa said: “It is expected that the most distant space boundary will expand dramatically.”

This is partly because the James Webb Space Telescope is scheduled to launch from French Guiana on October 31, 2021 and will inherit the Hubble Telescope tradition. Specifically, it will observe the infrared universe and detect light from distant old galaxies. Due to the interference from the atmosphere, infrared light cannot be well detected from the earth. Therefore, to detect the infrared universe, space-based telescopes are required.

” [James Webb Space Telescope] The observatory will detect the light emitted by the first-generation galaxies formed in the early universe after the Big Bang, and study whether the atmospheres of nearby exoplanets show signs of habitability,” said Eric Smith, a NASA Webb program scientist at the agency’s headquarters. (Eric Smith) said. The previous statement.


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