What's New at the AAO Weather out of this world Astronomers have found the first hints that failed stars known as brown dwarfs may have weather patterns with winds, clouds and storms. Dr Tinney of the Anglo-Australian Observatory and Mr Andrew Tolley, a student at the University of Oxford, recently observed a brown dwarf and noted changes in its surface chemistry as it rotated. The left panel shows the weather patterns we might expect on a brown dwarf if it looked like Jupiter. The right panel shows observed variations seen as the brown dwarf LP944-20 rotates. The arrows highlight strong episodes of cloud passage where very different signals are seen in the two colours observed.
Brown dwarfs are failed stars with masses in between that of Jupiter-like planets and normal stars.
For decades, scientists have suspected that brown dwarfs exist but the first confirmed detection came only a few years ago. Today, after 30 years of searching, less than 50 brown dwarfs have been discovered. Of these, only a handful are bright enough and close enough to be studied for weather. Tinney s team is leading Southern Hemisphere attempts to learn more about brown dwarfs. They are very faint, and extremely difficult to detect, and for Tinney and Tolley to have noted surface changes is remarkable.