A heavenly body that itself shines?

In our time, scientists know celestial bodies that emit light, they are called stars. The closest star to us is the well-known Sun.
Stars are huge balls of gas, in the depths of which complex (scientists call them thermonuclear) reactions occur. The stars emit not only light, but also heat. Unfortunately, the life cycle of stars is limited. After many millions of years, our star will go out, turn into a so-called dwarf.