Hunting brown dwarfs

Today the team behind the CoRoT space telescope report that they have found a rare example of a brown dwarf tightly orbiting its star. I asked CoRoT team member Suzanne Aigrain of Oxford University's Department of Physics about 'brown dwarf deserts', the gap between giant planets and stars, and what would happen if our solar system had its very own brown dwarf. OxSciBlog: What is a brown dwarf? - Suzanne Aigrain: A brown dwarf [BD] is a celestial object intermediate in mass between a planet and a star. It's helpful to recall the definition of a star: a star is a ball of gas held together by its own gravity and which radiates light produced by thermonuclear reactions in its core, mainly burning Hydrogen to produce Helium. A brown dwarf is an object very much like a star, but which is not massive enough to burn Hydrogen in its core. As such, brown dwarfs are faint and radiate mainly in the infrared, slowly releasing the heat they accrued during their formation. On the other hand, according to the International Astronomical Union's definition, a planet is also held by its own gravity but it is a) in orbit around a star or brown dwarf and b) not massive enough to burn Deuterium (Deuterium is an element which burns even more easily than Hydrogen). Any object which has a mass below the Hydrogen limit but above the Deuterium limit is thus a brown dwarf. This is the case for CoRoT-15b. The definitions I have given above leave a rather fuzzy area for the case of object which are below the Deuterium burning mass limit but are not in orbit around a star or brown dwarfs - these are sometimes called sub-brown dwarfs or free-floating planets. OSB: What is the significance of CoRoT finding a BD?