Astronomers find extreme weather on an alien world
A University of Toronto-led team of astronomers has observed extreme brightness changes on a nearby brown dwarf that may indicate a storm grander than any seen yet on a planet. Because old brown dwarfs and giant planets have similar atmospheres, this finding could shed new light on weather phenomena of extra-solar planets. As part of a large survey of nearby brown dwarfs - objects that occupy the mass gap between dwarf stars and giant planets - the scientists used an infrared camera on the 2.5m telescope at Las Campanas Observatory in Chile to capture repeated images of a brown dwarf dubbed 2MASS J21392676+0220226, or 2MASS 2139 for short, over several hours. In that short time span, they recorded the largest variations in brightness ever seen on a cool brown dwarf.
Title: High Amplitude, Periodic Variability of a Cool Brown Dwarf: Evidence for Patchy, High-Contrast Cloud Features Authors: Jacqueline Radigan, Ray Jayawar dhana, David Lafrenier , Etienne Ar tigau, Mark Marley, Didier Saumon
We present continuous photometric monitoring in the J, H, and Ks bands of the T1.5 dwarf 2MASS J21392676+0220226 using the Wide Field Infrared Camera on the DuPont 2.5-m telescope at Las Campanas. Observations spanning 100 days indicate that 2MASS J2139+0220 is variable with a period that is an integer multiple of 7.72 ± 0.05 hr, and a peak-to-peak amplitude as high as 30% in J. The amplitude and shape of the light curve vary on a timescale of days, suggesting that evolving atmospheric features - most likely heterogeneous clouds - are responsible.