Massive stars life cycle

Answer 1

Massive stars evolve in a similar way to small stars until it reaches its main sequence stage The stars shine steadily until the hydrogen has fused to form helium ( it takes billions of years in a small star, but only millions in a massive star).

The massive star then becomes a Red Supergiant and starts of with a helium core surrounded by a shell of cooling, expanding gas.

In the next million years a series of nuclear reactions occur forming different elements in shells around the iron core.

The core collapses in less than a second, causing an explosion called a Supernova, in which a shock wave blows of the outer layers of the star. (The actual supernova shines brighter than the entire galaxy for a short time).

Sometimes the core survives the explosion. If the surviving core is between 1.5 - 3 solar masses it contracts to become a a tiny, very dense Neutron Star. If the core is much greater than 3 solar masses, the core contracts to become a Black Hole.

1.nebula

2.protostar

3.blue giant, then it expands in to a

4.red super giant

5.super nova

6.then it cools in to a

black hole or a neutron star