The Death of Stars

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The Death of Stars : 

The Death of Stars

How Does a Star Die? : 

How Does a Star Die? Eventually, the hydrogen (the “fuel” for the nuclear fusion) in the center of the star will run out. No new heat is made and gravity will take over and the center of the star will shrink. This makes the very outside of the star “float up” and cool down, making the star look much bigger and redder - a Red Giant star.

The Second Red Giant Stage : 

The Second Red Giant Stage As the center collapses, it becomes very hot again, eventually getting hot enough to start a new kind of nuclear fusion with Helium as the fuel. Then the Red Giant shrinks and the star looks “normal” again. This does not last very long, though, as the Helium runs out very quickly and again the star forms a Red Giant.

The End of a Sun-Like Star : 

The End of a Sun-Like Star For a star like the Sun, no more nuclear fusion can take place, so the center of the star will keep collapsing. Eventually it can become almost as small as the Earth, but with the same mass as a whole star! This very dense object is called a White Dwarf. A piece of a white dwarf the size of a cellphone would weigh as much as an elephant on the Earth.

What is left after a Supernova? : 

What is left after a Supernova? Because the star was so big, the collapse does not stop even with a White Dwarf, but an even more dense object called a Neutron Star is made. The density of a Neutron star is about 1x1018 kg/m3 (that is 1,000,000,000,000,000,000!) Sometimes the collapse cannot stop at all and a Black Hole is made, from which not even light can escape! The debris of the explosion is blown away and forms a glowing cloud called a Supernova Remnant. Stars form in clouds of gas. Heat from nuclear fusion, and gravity balance. When the hydrogen fuel runs out, a Red Giant is formed. For Sun-like stars, a White Dwarf and Planetary Nebula are left. For massive stars, a Supernova explosion leaves behind a Supernova Remnant and a Neutron Star or perhaps even a Black Hole.

Stellar Evolution : 

Stellar Evolution

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