Question

A star at the stage in its life cycle when it stops burning hydrogen, begins burning

helium, and expands to a large, low-density star.
What stage in the life cycle does this describe?

Answer 1

A star like our Sun will become a white dwarf when it has exhausted its nuclear fuel. Near the end of its nuclear burning stage, such a star expels most of its outer material (creating a planetary nebula) until only the hot (T > 100,000 K) core remains, which then settles down to become a young white dwarf