Binary star size, luminosity, and approximate shape) of both members of the system. While a number of binary star systems have been found to harbor extrasolar planets, such systems are comparatively rare compared to single star systems. Observations by the Kepler space telescope have shown that most single stars of the same type as the Sun have plenty of planets, but only one-third of binary stars do. According to theoretical simulations, even widely separated binary stars often disrupt the discs of rocky grains from which protoplanets form. On the other hand, other simulations suggest that the presence of a binary companion can
Transfer DNA binary system Transfer DNA binary system A transfer DNA (T-DNA) binary system is a pair of plasmids consisting of a binary plasmid and a helper plasmid. The two plasmids are used together (thus "binary") to produce genetically modified plants. They are artificial vectors that have both been created from the naturally occurring Ti plasmid found in "Agrobacterium tumefaciens". The binary vector is a "shuttle vector", so-called because it is able to replicate in multiple hosts ("E. coli" and "Agrobacterium tumefaciens"). Systems in which T-DNA and vir genes are located on separate replicons are called T-DNA binary systems. T-DNA is located on the