What is the Life Cycle of a Star?

The theory of stellar evolution is a theory of astronomy about the evolution of stars during their lifetime. Since the evolution of a single star usually lasts billions of years, it is impossible for humans to observe it completely. The current theory is still partly a speculative hypothesis. At present, astrophysicists mainly observe a large number of stars, judge their different stages in life, and use computer models to simulate the evolution of stars.

Stellar evolution

Low mass stars

The end of the evolution of low-mass stars is not directly observed. The age of the universe is thought to be more than 10 billion years, not enough for these stars to run out of core hydrogen. Current theories are based on computer models.

Some stars undergo helium fusion in the core, producing an unstable and unbalanced reaction, and a strong solar wind. In this case, the star will not burst to produce a planetary nebula, but will only run out of fuel to produce a red dwarf.

But stars less than 0.5 times the mass of the sun will not produce a helium reaction in the core even after hydrogen is depleted. Red dwarfs such as neighboring stars have a life span of hundreds of billions of years. After the core reaction ends, red dwarfs gradually fade in the infrared and microwave bands of electromagnetic waves.

Medium-mass stars

When stars like the sun die, they become planetary nebulae, like

After a star runs out of its fuel, based on its mass during its lifetime, if the hypothetical

Molecular cloud original stellar main sequence star red giant planetary nebula white dwarf black dwarf red supergiant supernova neutron star black hole