What term is used to describe a dying star which has progressed beyond the red giant stage and is extremely dense and comparable in size to the Earth? just need the term!!!
The specific term for such a star is a "variable star."
A star in this stage is called "variable" because the size and conditions under which the star is burning vary, depending upon the remaining amount of fuel to burn and how that fuel reacts to other elements remaining in the core of the star. A red giant becomes a "variable star" when it has used up almost all of the hydrogen that had been the fuel in its core. The core contracts and begins to burn helium. Any remaining hydrogen eventually is joined to the helium, which is consumed quickly since helium burns easily and at a very high temperature.
When the helium is exhausted, the outer shell of the star expands and becomes much brighter, while the core contracts to approximately the size of the Earth. The shell, or the remains of the star's atmosphere, eventually separates and forms a planetary nebula, while the core is left to cool as a white dwarf.