Type I
1)Two stars are involved. They are called binary stars. They go around each other.
2)One star is usually bright and big, the other is dim and small, like a white dwarf.
3) The white dwarf has great mass, great density, and strong gravity.
4) The big, bright star has less gravity.
5) The gravity from the white dwarf pulls gases from the big, bright star.
6) Mass is taken from the big bright star and added to the white dwarf.
7) Temperature of the white dwarf is not high enough to equalize this new mass, so gravity just pulls and pulls, increasing the mass until the white dwarf star collapses.
8) The energy of the collapse makes the temperature rise very high, very quickly.
9) This reaction makes the star blow up. This is a supernova. Almost all of the star’s mass is blown into space. A huge cloud of gases is formed. What is left may become a neutron star.
Type II
1)Produced by a star which is not part of a binary star.
2)Its mass must be at least 8 times greater than the Sun’s.
3) It uses up its hydrogen quickly, then begins to contract.
4) This contraction makes the star hotter.
5) Then helium begins to fuse, becoming carbon and oxygen.
6) This time energy is released, causing the star to expand.
7) When the helium fuel is used up, the temperature begins to drop quickly.
8) The outward pressure drops and the star collapses.
9) The energy of the collapse makes the temperature rise very high, very quickly.
10) This process of creating new elements through fusion (giving off energy, expanding), then contracting when the fuel is used up, then fusing into new, heavier elements, continues until the star’s core is iron.
11) Since iron does not fuse, there is no more outward energy. But the gravity of this massive star is so great, it pulls the star in, collapsing it.
12) The core of the star gets very small, about 5-100 miles across.
13) When the star collapses, shock waves go out causing a huge explosion, a supernova. Almost all of the star’s mass is blown into space. What is left may become a neutron star.