[Telepathic Intruder]

"Brown dwarfs don't have enough mass to cause nuclear fusion in their cores the way stars do."

One of the defining characteristics of brown dwarfs is that they do in fact produce nuclear fusion, but using deuterium which is only about 20 ppm of hydrogen. It's enough to make them glow brightly in infrared which is why we can detect them. This occurs in Jupiter-like objects between about 13 and 75 solar mass.

[Red Badger]

Seem like to me that they could grow and accrete more material as time goes by and eventually become a shiny new star..........................

[Telepathic Intruder]

Between 13 and 75 Jupiter mass, I mean.