- A star is born from a molecular cloud in space. The spiral arms of certain galaxies serving as nurseries. Dense sections begin coming together, eventually forming a protostar.
- As the protostar collects matter--a process known as accretion--it heats up. when it reaches 15 million C, nuclear fusion begins, and hydrogen gases fuse to make helium.
- Once fusion starts, the star releases energy and begins to shine. This phase of a star's life is called a main sequence. The sun is a main sequence star.
- During its main sequence, a star contracts, making its core temperature rise. Meanwhile, the hydrogen has fused into helium. Then the helium begins fusing into carbon.
- With the helium fusing to carbon, the star expands and cools. It now has become a red giant. Red giants don't shine as brightly as main sequence stars.
- Once the star exhausts its fuel, which takes millions upon millions of years, what happens next depends on the size of the star. A low-mass star would turn into a white dwarf. A star of medium mass would go supernova, then turn to a neutron star. Massive stars would become black holes.
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