What's a Brown Dwarf Star? First we'll explain WHAT these astronomers have discovered. Then we'll discuss HOW they discovered it. At the risk of being scientifically vague, I'll try to explain the current understanding of how stars and planets form in space. All matter attracts other matter. A larger mass will attract smaller masses towards it. In space this results in growing clouds of matter that tend to clump together and attract more matter. Since most of the matter in space is gaseous, these clouds eventually get so dense that they collapse into dense gaseous spheres. When they do this there is usually some "left over" matter that forms a ring around the sphere.If there is enough matter in a sphere of hydrogen, for example, it can cause so much compression at the shpere's core that the hydrogen atoms begin to fuse together and a fusion-reaction ignites a new born star. In this reaction two hydrogen atoms join together to form one helium atom and release extra energy as radiation. Scientists believe that the minimum mass needed to ignite a sun is about 13 times the known mass of the planet Jupiter -- written as "13MJ." If the mass is lower than this, the pressure in the core is not enough to ignite and the sphere will be hot ball of gas called a "brown dwarf." As a new star spins, the disk surrounding it gradually cools and the matter forms heavier elements like metals and minerals. These "rocks" eventually clump together and form solid spheres called planets. Sometimes a solid sphere will attract some of the gas that is in the disk and this will result in a gaseous giant, like Jupiter and Saturn, which has a solid core but a thick gaseous atmosphere. These "gas giant" planets can be very massive but, because of their solid cores, they will never ignite and become stars.
This newly discovered "brown dwarf" is believed to have formed from the same condensed matter that gave birth to our Sun. It is believed that, after the large planets formed around the Sun, they pushed it to the edge of the Solar system where it formed a sphere about 1.9MJ -- well below the mass needed to ignite it as a "sun."Many suns that we observe in the galaxy are part of binary systems or double stars. There is debate about how two suns form from a single condensed cloud of matter. Some believe that they both form at the same time; others believe they split following the creation of one huge sun. Sometimes both spheres are capable of fusion and both suns shine brightly, encircling each other around an imaginary point call the barycenter. Sometimes only one sun attains 13MJ and ignites, while its smaller companion, the brown dwarf, glows dimly and radiates heat. Astronomers usually can only see the brightest of the two, but because they both circle around a common barycenter, the wobble reveals the mass of the unseen companion. We are close to our Sun and within its gravitational influence. So as we are travel through space, it appears to us that the G1.9 is moving in an elipse between our furthest planetoid, Pluto, and the edge of our Solar system, near the Oort Cloud. - View Zone.
NOTE: Special thanks to Joann Chan-McKeon for contributing to this post.