ANTARIKSA — Stars are celestial bodies that experience stages of life like humans. From birth, growth and then destruction.
There are several stages of a star’s life ranging from star birth, main sequence, red giant, white dwarf and supernova.
Star Life Process
Reporting from Earth Sky, stars radiate energy by converting hydrogen into helium through nuclear fusion. This process is what causes the sun to emit light, heat and other forms of energy.
The process of nuclear fusion in stars initially requires hydrogen. Stars do not have an unlimited supply of hydrogen. One day, the hydrogen in the star will run out.
The sun converts about 600 million tons of hydrogen into helium every second. The sun has enough hydrogen to last about 10 billion years.
The consumption of hundreds of millions of tons of hydrogen per second does not necessarily use up the hydrogen in the Sun. Only 0.7 percent of the hydrogen consumed by the sun in the fusion process will ultimately be emitted as energy.
The remainder is used to convert hydrogen atomic nuclei into helium atoms. That small percentage of energy has given us all the light and heat we have gotten from the sun over the last 4.5 billion years.
Astronomers estimate that our star is now about 4.5 billion years old. If we compare it to a human, the sun is now entering middle age.
Scientists call the current stage of our star’s life the hydrogen burning phase. That’s because the energy source is the fusion of hydrogen atoms.
Stars that burn mostly hydrogen are in the main sequence phase. As a main sequence star, the sun is in a state called stellar equilibrium. That is, the outward radiation pressure from the sun’s internal fusion reactions balances the inward gravitational pressure of the sun.
Main sequence, then subgiants and red giants
Eventually, as its nuclear fire weakens, the star begins to contract due to its own gravity. At the same time the star shrinks and its temperature increases. So the star becomes brighter.
In aging stars, these phases of shrinking and brightening can last for several million years. If a star begins to become brighter, it means that the star has begun to evolve into what is known as a subgiant star. This is an intermediate phase between the main sequence and the red giant stage.
2023-11-11 23:50:00
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