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write a short note on evelution of sun like a star

Evolution of the Sun

The spinning disk of dust and gas from which the Sun and solar system formed is called the solar nebula. A million years after it started forming, the embryonic Sun probably went through a phase, called a T-Tauri phase, where it emitted an intense solar wind. This 'wind' of solar particles may have had an important role in modifying young planetary surfaces.

The material at the centre of the solar nebula continued to collapse until after perhaps ten million years, the heating due to this gravitational collapse became great enough for the Sun to become a ball of plasma - a state achieved when electrons are stripped off atoms, leaving positive ions behind.

Temperatures became so high that thermonuclear fusion started. Once the Sun's power source had been turned on, the dusty, early inner solar system would have been heated until the dust grains were vaporised. As the Sun settled down, the nebula could start to cool and planets to form.

Today, at approximately 4.6 billion years after the Sun's birth, some 37% of the hydrogen fuel has been turned into helium. At the current rate of burning, the Sun has about another 5 billion years before it runs out of hydrogen. When that happens, other nuclear reactions involving carbon, nitrogen and oxygen will start. The core will contract and burn at higher temperatures but the Sun as a whole will become a red giant.

Its outer, light gas envelope will expand to beyond Earth's orbit, engulfing the Earth and warming the outer solar system.

Before this occurs, another problem for life on Earth will emerge. When it was born, the Sun was only 70% as bright as it is now. By comparing it with other stars we know that it will evolve to perhaps double its current brightness in five billion years and Earth's oceans will have boiled away leaving a sterile planet.

After it spends some time as a red giant, the Sun's nuclear reactions will stop and it will collapse to become a white dwarf. Without a source of power it will then slowly fade into oblivion becoming a black dwarf.

hope the info. helps....