Many stars are connected to a group. Stellar clusters allow astronomers to study the life of stars, and astronomy enthusiasts provide great views. So let's look at these star cities.

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In space, there are clusters connecting from several to about a million stars. They are held together by gravity and they move in space just like a school of fish. The stars that make up the given cluster were created in a similar time and from the same matter. They usually have a similar chemical composition. There are two types of star clusters:

Open cluster

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These are clusters of not a large number of stars. The largest number of them are several thousand. In our galaxy, we have known about 1,200 open clusters. The smallest of them are about a few light-years in diameter, and the largest are really very wide. The most known open clusters are the Pleiades (M45) in the constellation of Taurus, h and chi Persei in Perseus and the manger cluster (M44) in the constellation Cancer. These types of clusters occur mainly in the arms of spiral galaxies, where new stars are born. Open clusters are relatively unstable. These clusters last for no more than several hundred million years.

Globular cluster

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They are dense clusters of a huge number of stars, often many millions. They are packed quite close together in an area up to 100 light-years in diameter. The most known globular cluster is Omega Centauri, unfortunately only visible from the southern hemisphere. In our hemisphere, Cluster of Hercules (M13) reigns supreme. Most globular clusters are on the outskirts of the galaxies, in the galactic halo (glow surrounding the galaxy). Globular clusters are long-lasting and very old. Their age is estimated at around 11-12 billion years. This is only a little less than the age of the entire universe.

Greetings to lovers of Astronomy!

Sources:
Star cluster
Open cluster
Globular cluster
and my knowledge...

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