Looking at the night sky, you can get a glimpse of the stars from hundreds of billions of galaxies. Some galaxies are blue disks that swirl like our own Milky Way, others are red spheres or malformed, clumsy mess or something in between. Why are they different configurations? It turns out that the shape of a galaxy tells us something about the events of the galaxy’s ultra-long life.
At a very basic level, there are two categories of galaxy shapes. It is a disk and an oval. The disc galaxy, also known as the spiral galaxy, is shaped like a fried egg, says Cameron Humels, a theoretical astrophysicist at the California Institute of Technology. These galaxies, like the yolk, have a more spherical center surrounded by gas and circumstellar discs — egg white. The Milky Way and our closest galaxy neighbor Andromeda fall into this category.
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Theoretically, a disc galaxy is initially formed from a cloud of hydrogen. gravity Attract gas particles together.As hydrogen As the atoms approach, the clouds begin to rotate and their collective mass increases. This also increases the gravity of the atom. Eventually, gravity causes the gas to collapse into a swirling disk. Most of the gas is at the edges that supply star formation. Edwin Hubble, who confirmed the existence of galaxies beyond our galaxy only a century ago, called the disc galaxy a late galaxy. According to NASA..
Alternatively, elliptical galaxies (what Hubble called early galaxies) look old. Instead of rotating like a disc galaxy, the stars of an elliptical galaxy move more randomly, according to observational astrophysicist Robert Bassett, who studies galaxy evolution at Swinburn University in Melbourne, Australia. I will. Elliptical galaxies are thought to be the product of galaxy mergers. When two galaxies of the same mass merge, the stars begin to pull each other under gravity, impeding the rotation of the stars and creating a more random orbit, according to Basset.
Not all mergers result in elliptical galaxies. The Milky Way is actually quite old and large, but it retains its disk shape. We are increasing its mass by simply pulling in dwarf galaxies, which are much smaller than our home galaxy, and collecting free gas from space. But our disk-shaped sister galaxy, Andromeda, is actually heading straight toward the Milky Way, Basset told Live Science. So, billions of years later, two spiral galaxies could merge, with each of the duo’s starry disks canceling each other’s rotations, creating a more random elliptical galaxy.
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These mergers are far from instant. They take hundreds of millions of years, and even billions of years. In fact, from our point of view, it’s going so slowly that a merger that looks static is underway. “They are basically in exactly the same state and are the same for all human civilizations,” Basset said. Hubble gave these galaxies their own classification, an irregular galaxy. To see them, “they are usually confused by multiple components,” Hummel said. “The irregular galaxy looks like the wreckage of a big train,” Basset added.
Finally, less common shapes of lenticular galaxies appear to be a mixture of elliptical and disc galaxies. According to Basset, existing stars may begin to interact when the disc galaxy runs out of all its gas and is unable to form new stars. Their gravitational pull creates a shape that looks like a lentil — a kind of oval, but still a spinning disk.
What scientists have revealed so far about galaxies and their 3D shapes has been speculated by using thousands of 2D images and filling in the voids depending on other properties such as galaxy color and movement. Mr. Bassett said.
For example, the young age of disc galaxies is supported by their blue color. Blue stars are generally larger, faster, and burn hotter (blue light has higher frequencies and therefore has more energy than red light).Elliptical galaxies, on the other hand, are filled with old stars — called rEd Dwarf — It’s not burning so hot or fast.
Still, despite all we have learned about the huge celestial structures around us, there is still much we do not know, Hummel said.
“Galaxy formation and evolution is one of the biggest open problems in the fields of astronomy and astrophysics,” said the Hummel figurines.
Originally published in Live Science.