How small are the smallest celestial objects that form like stars, but don’t produce their own light? How common are they compared to full-fledged stars? How about “rogue planets,” which formed around stars before being tossed into interstellar space? When NASA’s James Webb Space Telescope launches in 2021, it will shed light on these questions.
Source:
https://phys.org/news/2019-12-nasa-webb-telescope-young-brown.html