Understanding Different Types of Galaxies: Disk vs Elliptical Galaxies

KOMPAS.com – The Milky Way Galaxy is only one of the galaxies in this universe.

The galaxy is described as having the shape of a rotating blue disk. But interestingly, it turns out that there are various forms of galaxies, not just disk-shaped.

Kinds of galaxies

Quoted from Live Science, Monday (3/7/2023) at the basic level, there are two classifications of galaxy shapes, namely disks and ellipses.

According to Cameron Hummels, a theoretical astrophysicist at Caltech, disc galaxies, also called spiral galaxies, are shaped like a fried egg.

The galaxy has a more rounded center, like an egg yolk, surrounded by a disk of gas and stars. The Milky Way and Andromeda, which are our closest galactic neighbors, fall into this category.

In theory, disk galaxies were originally formed from hydrogen clouds. Gravity then holds the gas particles together.

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As the hydrogen atoms approach, the cloud begins to rotate and its collective mass increases which causes its gravitational force to increase as well. Eventually, gravity causes the gas to collapse into a spinning disk.

Most of the gas is at the edges, feeding star formation.

Edwin Hubble, who confirmed the existence of galaxies outside our galaxy, said that disk galaxies are late-type galaxies because they formed later in the history of the universe.

Meanwhile, the elliptical galaxy that Hubble calls an early-type galaxy looks older.

Instead of rotating like disk galaxies, stars in elliptical galaxies have a more random motion. Elliptical galaxies are thought to be the product of galaxy mergers.

When two galaxies of the same mass merge, their stars begin to attract each other with gravity, disrupting the stars’ rotation and creating more random orbits.

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2023-07-03 13:00:00
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