Ross 19B is likely the coldest brown dwarf found around a main-sequence star, as of July 2024.

[3] Ross 19B (also called CWISE J021948.68+351845.3) was initially found in the Backyard Worlds project by the citizen scientists Samuel Goodman, Léopold Gramaize, Austin Rothermich, and Hunter Brooks.

It was then observed by the professional astronomers of the paper led by Adam C. Schneider with the Keck Observatory in 2020, measuring a J-band magnitude of 21.14 ± 0.02.

Ross 19B has a very low temperature of about 400–615 kelvins (127–342 °C; 260–647 °F), making it either a late T-dwarf or a Y-dwarf.

Its wide separation results in an extremely low gravitational binding energy.