star classObservedMeasured or catalogued in the real sky, with its source cited.ModelPublished physics or a published model, applied as written.
Red giant
A star in a late stage of life that has run out of hydrogen in its core and swollen to tens or hundreds of times the Sun's size, with a cool, orange-red surface. Stars from about 0.8 to 8 solar masses pass through this stage; the Sun will, in about seven and a half billion years.