Measuring the Coldest Brown Dwarf

Artist’s rendering of how WISE 0855 might appear if seen close-up in infrared light. Illustration by Joy Pollard, Gemini Observatory/AURA

Gemini has made spectral observations of the coldest known brown dwarf, which has a temperature of only about 250K. The object, known as WISE 0855, reveals itself to look as much like Jupiter as any discovered exoplanet and exhibits evidence for water clouds in its atmosphere. Andy Skemer (University of California Santa Cruz) led this work, using the Gemini Near-Infrared Spectrograph (GNIRS) on Gemini North. The best conditions were required to catch the weak emission, which is five times fainter than any other object detected in ground-based spectroscopy in the 5μm atmospheric window. The Gemini press release includes links to video. A preprint is currently available online, and the work will be published in Astrophysical Journal Letters.