What defines the size of a star

What makes a star?

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How are stars formed?

When a star is formed, a cloud of gas and dust accumulates and begins to spin around itself faster and faster. This compresses the material in the middle more and more and creates heat.

At some point it gets so hot that hydrogen turns into helium inside the lump. Nuclear fusion occurs, which releases light and heat. The lump begins to glow - a star rises.

Star Factory: Orion Nebula

The "Orion Nebula" is one of the clouds closest to us in which stars are formed. It consists largely of hydrogen and is therefore perfectly suited as a star factory.

By observing with a new telescope, astronomers know that the stars there are produced in different bursts. It used to be assumed that the stars in a cluster are always the same age. Today we know that there are many thousands of years between the date of birth of the youngest and oldest stars.

Stars are different colors

These young stars shine less brightly than their bigger siblings. How bright you can see a star in the sky depends on its size and internal energy, but also on its distance from the earth. And you can also guess their temperature. In their colors.

Some stars shine bluish, others reddish or in other colors. This is because their surface has different temperatures. Blue stars are extremely hot, red stars are cooler in comparison.

Color and temperature of the stars

Blue: 35,000 degrees Celsius

Blue White: 20,000 degrees Celsius

Yellow white: 7,000 degrees Celsius

Yellow: 6,000 degrees Celsius

Orange: 5,000 degrees Celsius

Red: 3,000 degrees Celsius

Exploding stars

Sometimes stars also become unstable and break, then they explode.

Shortly before their end, however, they shine again particularly brightly.

Such a star explosion is also called a supernova. We rarely see a picture like the one captured here. It's a very special snapshot.