what happen when Rigel star dies?

What happens to whom? Us? Absolutely nothing. Do you know how far away Rigel is?

When Rigel star dies then it become a black hole where everything disappears even light and it start to attract other mass around it and shallow it which makes it more strong black mass with great gravity.

Unfortunately, supergiant stars reach the end of the line once all the remaining silicon fuel has undergone nuclear fusion to create a core of iron. Iron requires more energy to fuse than the energy it releases, so it won’t burn like the other elemental fuels. With no burning to push back against the crushing force of gravity in so large a star, the core collapses and sends out shock waves that rip it apart in a supernova explosion.

- See more at: http://astrobob.areavoices.com/2013/01/05/meet-rig...

It will become either a neutron star or a black hole depending on its mass.

It will become a neutron star