Which type of stars is very hot but gives off little light? dwarfs giants main sequence stars nebula

dwarfs

The matter in a white dwarf no longer supports fusion resistance, therefore the star has no source of energy. As a consequence, it cannot sustain itself by the energy produced by heating against gravitational breakdown but is sustained only by electron degeneration pressure, causing it to be notably dense.  

The degenerate matter that forms up the mass of a white dwarf has very low obscurity, in other words, it does not dissipate heat and light much by transmission. Eventually, all white dwarfs will freeze down into black dwarfs, because they lack the power to create light.