Question

An explosion that destroys the outer portion of a star is known as a

Answer 1

The question is asking to states the term that states an explosion that destroys the outer portion of a star, and base on my research, I would say that it is a Supernova, which is due to the death of a star.  I hope you are satisfied with my answer and feel free to ask for more if you have question and further clarification

Answer 2

A supernova. This happens towards the end of the lifetime of a star. It is a massive explosion that eventually causes the collapse of a star which eventually will turn into a black hole. Sometimes when a start explodes it will shine brightly for weeks or months before eventually fading into black.