The First Photograph of a Planet Orbiting a Binary Star System (1995)
This description pertains to the first photograph of a planet orbiting a binary star system, taken in 1995. The photograph was taken by the Hubble Space Telescope and shows the planet, named HD 188753 Ab, orbiting the two stars of the HD 188753 system. This discovery was a major breakthrough
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars are among the most important objects in astrophysics because they allow direct measurement of stellar masses and test theories of stellar evolution. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars using a telescope, in which case they are called visual binaries. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy or astrometry. If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called eclipsing binaries, or, together with other binaries that change brightness as they orbit, photometric binaries.