WASP-39b, officially named Bocaprins, is a "hot Jupiter" extrasolar planet discovered in February 2011 by the WASP project, notable for containing a substantial amount of water in its atmosphere. In addition WASP-39b was the first exoplanet found to contain carbon dioxide in its atmosphere, and likewise for sulfur dioxide.
Exoplanet WASP-39b artist's concept
Comparison of "hot Jupiter" exoplanets, including WASP-39b (top row; 4th from left) (artist's concept). From top left to lower right: WASP-12b, WASP-6b, WASP-31b, WASP-39b, HD 189733b, HAT-P-12b, WASP-17b, WASP-19b, HAT-P-1b and HD 209458b.
Hot Jupiters are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods. The close proximity to their stars and high surface-atmosphere temperatures resulted in their informal name "hot Jupiters".
An artist's impression of a hot Jupiter orbiting close to its star.
Hot Jupiter with hidden water
Comparison of "hot Jupiter" exoplanets (artist concept). From top left to lower right: WASP-12b, Boinayel, WASP-31b, Bocaprins, HD 189733b, Puli, Ditsö̀, Banksia, HAT-P-1b and HD 209458b.