Question

With no nuclear reaction occurring, are brown dwarfs visually observable?

Answer 1

Brown dwarfs do glow with visible light, but they are not very luminous and emit mostly in infrared wavelengths. They are more likely to be reddish than brown.

Explanation:

Brown dwarfs are heated to temperatures where we can see them (dimly) by gravitational compression, and fusion of deuterium and lithium (which requires lower core tempeatures than ordinary hydrogen fusion).