Binary Star

The importance of binaries lies in a number of areas: 1) The analysis of a visual binary (where the two An x-ray image of the x-ray binary star system LMC X-1 in the Large Magellanic Cloud (LMC). LMC X-1 is seen as the two bright objects at center left and center right. The Tarantula Nebula is at the top of the cloud at left. The picture was taken by the ROSAT x-ray astronomy satellite. ROSAT discovered 15 new x-ray sources in the LMC, which is 163,000 light years from our galactic center and 33,000 light years in diameter. ROSAT was launched on June 1, 1990, and is a collaboration between Germany, UK, and USA. © Max-Planck-Institut Fur Physik Und Astrophysik. Photo Researchers, Inc. Reproduced by permission. components can be seen visually through a telescope) leads to the only direct method for the evaluation of stellar mass, one of the most important parameters of the physical universe. In some cases the mass of the system is found, in other situations the mass ratio of the components, and in some the individual masses can be determined; 2) Stellar duplicity plays an important role in the study of the physical aspects of stars, such as relative diameters, surface brightness, the genesis and evolution of stars, and the study of stellar-mass loss.