Take a look at the night sky and you will see the stars of hundreds of billions of galaxies. Some galaxies revolve around a blue disk like our own galaxy, others are red spheres or mispen, clumsy messy or something in between. Why different configurations? It turns out that the shape of the galaxy tells us something about the ultra-long life events of that galaxy.
At a very basic level there are two classifications for galaxy shapes: disk and ellipse. The disk galaxy, also called the spiral galaxy, is like a fried egg, said Cameron Hummel, a theoretical astrophysicist at Caltech. These galaxies have more spherical centers, yolk-like, surrounded by gas and stellar disks – egg whites. The Milky Way galaxy and our nearest galaxy Andromeda fall into this category.
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In theory, the disk galaxy initially formed from clouds of hydrogen. Gravity Draws the gas particles together. As Hydrogen As the atoms get closer, the cloud begins to move and their mass increases, causing their gravitational force to go up as well. Eventually, the gas fills up in a rotating disk due to gravity. Most of the gas is in the rim, where it feeds the star formation. Edwin Hubble, who just a century ago confirmed the existence of galaxies of our own, called disk galaxies late-type galaxies because of their shape meant they formed later in the history of the universe, According to NASA.
Alternatively, elliptical galaxies – what Hubble called early-type galaxies – look older. According to observation astronaut Robert Bassett, who studied galaxy evolution at Swinburn University in Melbourne, Australia, disk galaxies, like disk galaxies, have more random stars in elliptical galaxies than rotation. Elliptical galaxies are thought to be the product of galaxy mergers. When two sets of identical constellations merge, their stars begin to pull at each other with gravity, disrupting the star’s rotation and creating a more disordered orbit, Busset said.
Not every merger results in an elliptical galaxy. The galaxy is actually quite old and large, but retains its disk shape. It is simply increasing its mass by drawing in dwarf galaxies, which are much smaller than our home galaxies, and collecting free gas from the universe. Still, our disc-shaped sister galaxy, Andromeda, actually leads to the galaxy, Busset told Live Science. So billions of years from now, two spiral galaxies could merge and each starry disk of the two would offset the rotation of the other, creating a more random elliptical galaxy.
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This merger is far from immediate. They take millions, even billions of years. In fact, there are ongoing mergers that are moving so slowly – from our point of view – that it looks stable. “They’ve been basically the same, the same for all of human civilization,” Bassett said. Hubble gave these galaxies its own classification – the irregular galaxy. To see them, “they’re usually messed up with a lot of ingredients,” Hammel said. “Irregular galaxies just look like the wreckage of a big train,” Bassett added.
In the end, the less common shape seems to be a combination between the lenticular galaxy ellipse and the disk galaxy. It could be, Bussett said, that existing galaxies start to interact when the disk galaxy uses up all of its gas and can’t create any new stars. Their gravitational tugs form a shape on top of each other that looks like a lentil – an elliptical type, but a rotating disc.
Using thousands of 2D images about the galaxy and its 3D shapes, and based on other properties such as blackness color and motion, Bassett said, the assessment was made to fill in the blanks.
For example, the young age of disc galaxies is colored by their blue color. Blue stars are usually larger, and they become faster and warmer (blue light has a higher frequency and is more powerful than red light). Meanwhile, elliptical galaxies are filled with older stars – called rEd Dwarfs – It’s not too hot or burning fast.
However, even though we have learned about the vast celestial constructions around us, we still do not know much, Hammel said.
“Galaxy formation and evolution is the biggest open question in the field of astronomy and astrophysics,” Hammel said.
Published on Original Living Science.