With no nuclear reaction occurring, are brown dwarfs visually observable?
1 Answer
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).