The primary, SCR 1845−6357 A, is an
ultra-cool red dwarf,
one of the smallest and
coolest stars so far discovered, with a mass of about 7% of the
Sun's, a radius 9.4% of the
Sun's, and an
effective temperature of . It is very faint, at an
apparent magnitude of 17.4 due to its low
luminosity, equivalent to 0.03% of the
Sun's luminosity across all wavelengths. It was discovered in 2004 by the SuperCOSMOS survey. This star has been found to have a
brown dwarf companion in 2006, designated . The companion has an
observed distance of 4.1
AU from the primary and is classified as a
T-dwarf. It is estimated to have 25 to 65 times the
mass of Jupiter (2.4 to 6.2% of the Sun's mass), but its radius is 30% smaller than
that of Jupiter, about 50,000 km ( miles). It has an
effective temperature around . == Gallery ==