Friday, May 20, 2016

Clouds of Water on a Cold Brown Dwarf

Figure 1: Artist's rendering of Jupiter.

WISE 0855 is the coldest brown dwarf known. It has an effective temperature of only ~250 K. This is comparable to the atmospheric temperatures found on Earth, Mars, Jupiter and Saturn. WISE 0855 is estimated to have between 3 to 10 times the mass of Jupiter, and it is located ~7.5 light years away. WISE 0855 provides a good opportunity for the direct study of an object with similar physical characteristics as Jupiter. Observations of WISE 0855 with the Gemini-North telescope located near the summit of Mauna Kea in Hawaii revealed the presence of atmospheric water vapour and clouds on WISE 0855. The spectrum of WISE 0855 appears remarkably similar to Jupiter's. 

Figure 2: Temperature-pressure profiles of Jupiter, WISE 0855 and Gl 570D. Two dashed lines show the boundaries where H2O gas and NH3 gas begin to condense into clouds composed of H2O ice and NH3 ice. Skemer et al. (2016)

Skemer et al. (2016), "The First Spectrum of the Coldest Brown Dwarf", arXiv:1605.04902 [astro-ph.EP]