What is the shortest stage in a stars life cycle?

Answer 1

[Previous Answer: do you know what a star is? i do its a dog in the sky that runs really fast and is on fire..] That answer was not terribly helpful, here's something from the NASA website (edited slightly) which offers a cursory explanation, if anyone else wants to provide deeper explanation, please do, including how it is that we know the composition of a star during different stages in its life: Stars that are yellow-white, like our Sun are adult stars that are shining by hydrogen fusion. Toward the end of their normal lives, the stars become cooler and larger. These late-life stars might appear to take on more of an orange color.

Even later in their life cycles, the stars continue to cool down and expand in size, becoming red giants. These bright red stars swell to many times larger than our Sun's size and begin to shed their gaseous envelopes.

After ejecting most of their mass and exhausting much of their hydrogen fuel, the stars appear brilliant blue. Only a thin layer of material covers their super-hot cores. These stars are desperately trying to extend their lives by fusing helium in their cores. At this stage, they emit much of their light at ultraviolet wavelengths.

When the helium runs out, the stars reach the end of their lives. Only their burned-out cores remain, and they are called white dwarfs. White dwarfs are no longer generating energy through nuclear fusion and have gravitationally contracted to the size of Earth. They will continue to cool and grow dimmer for many billions of years until they become dark cinders.

Interestingly, stars can acquire a new lease on life when they collide and merge with other stars. The encounters boost the stars' energy-production rate, making them appear bluer. These stars are referred to as "blue-stragglers."

Answer 2

When a star starts to die, it expands, for example, in about 5 billion years the sun (Which is a star) will have expanded to about 250 times it current size, while losing about 30% of its mass.

If you want more information on the Formation and evolution of a star:

http://en.wikipedia.org/wiki/Star#Formation_and_evolution

Answer 3

The order is Nebula, Protostar, main sequence, then it splits into red giant, planetary nebula, white dwarf ,black dwarf then the other way is super giant, supernova, neutron star, black hole :) hope that helps

Answer 4

Giant stage which lasts about a billion years.

Answer 5

The Pro-star