Stars form from nebulae through gravity and fusion.

What happens when stars run out of fuel?

Stars contract and expand, forming heavier elements.

How do stars evolve based on their size?

Stars can become red giants or red supergiants.

Red giants become white dwarfs and then black dwarfs.

Red supergiants can undergo supernova explosions.

Stars evolve from nebulae to protostars through nuclear fusion, becoming main sequence stars, like the sun, which eventually run out of fuel and undergo contraction and expansion phases to form heavier elements.
The size of stars determines their evolution into red giants or red supergiants, with red giants transforming into white dwarfs and then black dwarfs, while red supergiants may explode into supernovae, potentially creating neutron stars or black holes.

How do stars form?
Stars form from nebulae through gravity and fusion.
What happens when stars run out of fuel?
Stars contract and expand, forming heavier elements.
How do stars evolve based on their size?
Stars can become red giants or red supergiants.
What is the final stage of a red giant star?
Red giants become white dwarfs and then black dwarfs.
What happens to red supergiants at the end of their life cycle?
Red supergiants can undergo supernova explosions.

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Stars begin their life cycle as a nebula, with gravity pulling dust and gas together to form a protostar that grows denser and hotter through nuclear fusion, eventually becoming a main sequence star.
Main sequence stars, like our sun, go through stable periods lasting billions of years until they run out of hydrogen fuel, leading to a contraction and expansion phase where heavier elements are formed based on the star's initial size.
Depending on their size, stars can evolve into red giants or red supergiants, with red giants transitioning into white dwarfs that eventually become black dwarfs, while red supergiants undergo supernovae explosions, potentially forming neutron stars or black holes.