A small review on Brown dwarfs

Recent Developments on Brown dwarfs: Brown Dwarfs Really Do Form Like Stars: Astronomers have uncovered strong evidence that brown dwarfs form like stars. Using the Smithsonian's Submillimeter Array, they detected molecules of carbon monoxide shooting outward from the object known as ISO-Oph 102. Such molecular outflows typically are seen coming from young stars or protostars. However, this object has an estimated mass of 60 Jupiters, meaning it is too small to be a star. Astronomers have classified it as a brown dwarf.[1]

Newborn Brown Dwarfs Stir Up The Neighborhood: Astronomers have found a clutch of jets from newborn brown dwarfs, bringing the total of these intriguing objects found to 4. New stars form in cold clouds of gas and dust. These so-called stellar nurseries are not only home to forming stars (protostars) but also harbour forming brown dwarfs.[2]

Stellar Stillbirths: Brown Dwarfs Revealed As Third Class Of Celestial Bodies After Stars And Planets: Brown dwarfs need to be treated as a separate class of celestial body in addition to stars and planets, researchers have found. Until now, brown dwarfs had been merely regarded as stars which were below normal size. However, they may well be stellar 'miscarriages.'[3]

What is Brown dwarfs ?

Brown dwarfs are sub-stellar objects with a mass below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores, as do stars on the main sequence, but which have fully convective surfaces and interiors, with no chemical differentiation by depth. Brown dwarfs occupy the mass range between that of large gas giant planets and the lowest mass stars; this upper limit is between 75[1] and 80 Jupiter masses (MJ). Currently there is some debate as to what criterion to use to define the separation between a brown dwarf from a giant planet at very low brown dwarf masses (~13 MJ ), and whether brown dwarfs are required to have experienced fusion at some point in their history. In any event, brown dwarfs heavier than 13 MJ do fuse deuterium and those above ~65 MJ also fuse lithium. The only planets known to orbit brown dwarfs are 2M1207b and MOA-2007-BLG-192Lb.[…]