Brown Dwarfs

This is the first ultra-cool brown dwarf discovered by NASA's Wide-field Infrared Survey Explorer.A brown dwarf is an object that didn’t quite make it to stardom. It’s sub-stellar without enough mass to sustain hydrogen-1 fusion like a main sequence star. Brown dwarfs fill a niche between large planets and lightweight stars, ranging unto about 75X the mass of Jupiter. Brown dwarfs with mass greater 13X MJ may be able to fuse deuterium, and dwarf’s with mass above 75X MJ may be able to fuse lithium.

WISE 0458+6434 was the first ultra-cool brown dwarf discovered by the Wide-field Infrared Survey Explorer. It’s the green dot in the picture above which is from infrared data coded as green and blue depending on wavelength. WISE 0458+6434 is a binary system of two (A and B) ultracool brown dwarfs. The primary (A) has a mass about 15X Jupiter’s and a surface temperature of around 600 K or about 330 C. That’s roughly a tenth of the surface temperature of the Sun. Brown dwarfs have found with surface temperatures as low as -150 C.

Image Credit: NASA

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