A white dwarf, a dense dead star, burns through its hydrogen before it can grow into a supernova. Identify the nonessential appositive phrase. A white dwarf a dense dead star hydrogen supernova

An appositive is a noun or a pronoun that renames another noun or pronoun. Appositives are placed directly after the noun or pronoun they identify. For example:

Bob's car, a wreck, died a grisly death by the side of the interstate.