Dec 23, 2019
OGLE-TR-122b
3,200 light years in the constellation of Carina, a star not too unsimilar to our sun has a binary companion that is the smallest known star. OGLE-TR-122b a red dwarf, is .12 solar radii, making it ever so slightly larger than the planet Jupiter, but has a mass of about 50 times Jupiter, thought to be the theoretical limit at which a star can become a star.
Any lower mass would likely be a brown dwarf.