Three stars are born

Three stars switch on

The gas in the cloud gathers in three places. The more tightly it is squeezed together, the hotter the middle gets. When the center passes about 10 million degrees, hydrogen starts to join together and give off light and heat. The star has switched on. They came from the same cloud, but each one gathered a different amount of gas.

Why?When you squeeze air hard into a small space, it heats up. A gas cloud heats up the same way as its own gravity squeezes its middle.

Learn moreWhen four hydrogen nuclei join into one helium nucleus, a tiny bit of mass turns into a lot of energy. This is called nuclear fusion. Stars are often born together in a group like this, called a star cluster.

When

Being born

Star we are watching

Three stars from one cloud

Size · state

Mass: 40 · 15 · 1 times the Sun