A global cloud map of the nearest known brown dwarf

• Published in: Nature (London) Vol. 505; no. 7485; pp. 654 - 656
• Main Authors: Crossfield, I. J. M., Biller, B., Schlieder, J. E., Deacon, N. R., Bonnefoy, M., Homeier, D., Allard, F., Buenzli, E., Henning, Th, Brandner, W., Goldman, B., Kopytova, T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.01.2014; Nature Publishing Group
• Subjects: 639/33/34/862; 639/33/34/867; 639/33/445/846; Astronomical research; Brown dwarfs; Dispersal; Dust; Global weather; Humanities and Social Sciences; letter; multidisciplinary; Natural history; Observations; Science; Sciences of the Universe; Silicates; Solar system; Space exploration; Weather patterns; Germany; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Instrumentation and Methods for Astrophysics; Astrophysics - Solar and Stellar Astrophysics
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature12955

A map of the surface of a brown dwarf reveals features that suggest patchy clouds, providing the mechanism for the dispersal of atmospheric dust as brown dwarfs cool with age. Casting a weather eye on a nearby brown dwarf The recently discovered system known as Luhman 16AB is a binary consisting of two brown dwarfs — objects much bigger than planets but not big enough to become stars — and is a mere six light years from us. Only Alpha Centauri and Barnard's star are closer. Ian Crossfield et al . have now mapped the surface of brown dwarf Luhman 16B in the infrared and find large-scale surface patterns indicative of patchy clouds. Monitoring suggests that the characteristic timescale for the evolution of global weather patterns is about one day. Further observations of the evolution of weather patterns on brown dwarfs could provide a new benchmark for understanding how global circulation conditions affect dusty atmospheres on brown dwarfs and giant extrasolar planets. Brown dwarfs—substellar bodies more massive than planets but not massive enough to initiate the sustained hydrogen fusion that powers self-luminous stars 1 , 2 —are born hot and slowly cool as they age. As they cool below about 2,300 kelvin, liquid or crystalline particles composed of calcium aluminates, silicates and iron condense into atmospheric ‘dust’ 3 , 4 , which disappears at still cooler temperatures (around 1,300 kelvin) 5 , 6 . Models to explain this dust dispersal include both an abrupt sinking of the entire cloud deck into the deep, unobservable atmosphere 5 , 7 and breakup of the cloud into scattered patches 6 , 8 (as seen on Jupiter and Saturn 9 ). However, hitherto observations of brown dwarfs have been limited to globally integrated measurements 10 , which can reveal surface inhomogeneities but cannot unambiguously resolve surface features 11 . Here we report a two-dimensional map of a brown dwarf’s surface that allows identification of large-scale bright and dark features, indicative of patchy clouds. Monitoring suggests that the characteristic timescale for the evolution of global weather patterns is approximately one day.