Protostars are pieces broken from the inside of the core star. Protostars don't emit their own lights because they're just clumps of dusts and clouds within the nebula. They can take about 100,000 years to reach the main sequence. It is important to know that a protostar is the birth of a star.
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what about our colors?
Color is one of ways to categorize stars. The early stage of a star is usually blue and later becomes red as it ages. At this time of the cycle, the star is young, bright, and extremely hot. Because they are so big and hot, they burn so much fuel and die rather quickly. During the mainstage life of the Giant Blue Star, the core starts to burn massive amounts of helium.
Great you asked! I will right it here on the board.
When the blue star converts all of the available hydrogen fuel in its core into helium, it becomes what is called a Red Giant Star. This occurs as the helium core temperature increase which causes the outer shell hydrogen fuse faster. The star expands, drops temperature, and changes color.