Q&A: Miscellaneous X-ray Sources
Is there such a thing as a red dwarf? If so, how is it different
from a white or brown dwarf?
A red dwarf is a star that has a mass between approximately 8%
and 50% of the mass of the Sun. It is different from a brown
dwarf in that its interior is hot enough to sustain hydrogen
fusion reactions as a supply of energy. It will eventually (in
20 billion years or so) turn into a white dwarf, a collapsed
star in which no nuclear reactions occur in the center. The
pressure for support against gravity is supplied by degenerate
electron pressure. See the entries in our Field Guide.