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The photo, sent in July from the James Webb telescope, looked unusual: like tree rings in space. A lot of theories about aliens immediately appeared, but the real explanation is much more elegant.
Photo that excited conspiracy theorists
Sent by “James Webb” in July, a mysterious image of a distant star system with rings diverging from the center has intrigued even some astronomers. Scientists joked that the photo looked like a “cosmic thumb print.”
The Internet was immediately full of conspiracy theories. Some users have claimed that the photo proves the existence of “alien megastructures” of unknown origin. However, a team of researchers from the University of Sydney disproved these speculations. Scientists have been studying the depicted object, the star WR20, for over 140 years. In an article in the journal Nature, they explained the strange process by which a cosmic body creates a dazzling pattern of rings visible in the photograph from the James Webb.
Wolf-Rayet stars
WR140 is a Wolf-Rayet star. They have a high temperature and sometimes throw a plume of dust into space, which is hundreds of times the size of the solar system. This phenomenon is called stellar wind. It is typical for all stars, but for those of this type it looks more like a stellar hurricane.
The nuclear radiation field around Wolf-Rayet stars is so intense that dust and wind fly out of the star’s upper atmosphere at a speed of 2–3 thousand km/s. This wind contains various elements (such as carbon) that escape into space and form dust.
Space dust column
WR140 is one of the few Wolf-Rayet-type stars that exists in a binary system, that is, it orbits another star, which is also a massive supergiant with its own stellar wind. Only a few such systems are known in the entire galaxy. In them, the dust does not just fly out of the star and form a hazy ball, but is formed in a cone-like region where the winds of two stars collide.
Since the binary system is in constant motion, the cone-shaped column of dust rotates with it. Because of this, it naturally curls into a spiral, like a jet from a garden sprinkler. Moreover, in WR140, both stars move not in circular, but in elliptical orbits, and the closer the stars are to each other, the more dust they emit. So every time at the point of closest approach, a column of dust rushes into space.
Almost perfect model
By simulating these effects, the team tracked the location of the columns of dust ejected from the stars. They then compared their model with photographs of the binary system taken at the Keck Observatory in Hawaii and found that it matched reality almost perfectly—with one exception. In the immediate vicinity of the star, the dust was not where it should have been. Scientists began to look for the reasons for this deviation.
The power of light
Light has momentum and can exert radiation pressure on matter. As a result, matter begins to move at great speed through space. This is a ubiquitous phenomenon, but it is very difficult to catch it. To see the acceleration of matter, it is necessary to accurately track its movement in a strong radiation field.
This acceleration turned out to be the only missing element in the models for the WR140. The discrepancy in the data arose because the rate of expansion of the dust layer was not constant: the dust was accelerated by radiation pressure. Scientists emphasize: “With each passage of the orbit, the star seems to deploy a sail of dust. When it catches the intense radiation emanating from the star, the dust sail makes a sharp jerk forward.
Dust rings in space
The result of the processes described above is strikingly beautiful. The WR140 releases dust rings every eight years, and the wind inflates the dust shell like a balloon. Eight years later, two stars begin a new orbit, and another shell appears, growing inside the predecessor. They keep piling up like a set of giant matryoshka dolls.
Opening confirmation
The scientists emphasize: “The true understanding of how correctly we selected the mathematical model came to us only after the image from the James Webb was received in June. The photo shows more than 17 dust rings, each of which is almost an exact copy nested in the previous one. The oldest of them was launched about 150 years ago.