The twins of the stellar world are binary star systems.A binary star is a star system consisting of two stars orbiting around their common center of mass.When two stars appear close together in the sky, the situation is known as an “optical double”. This means that although the stars are aligned along the same line of sight, they may be at completely different distances from us. This occurs in constellations; however, two stars in the same constellation can also be part of a binary system.
Artist’s impression of the sight from a (hypothetical) moon of planet HD 188753 Ab (upper left), which orbits a triple star system( yes, a Triple Star system!). The brightest companion is just below the horizon.
Binary star systems are very important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined, which in turn allows other stellar parameters, such as radius and density, to be indirectly estimated. This also determines an empirical mass-luminosity relationship (MLR) from which the masses of single stars can be estimated.
It is estimated that approximately 1/3 of the star systems in the Milky Way are binary or multiple, with the remaining 2/3 consisting of single stars.
The Brightest star in the sky is a binary.
This is true. When it was discovered in 1844 by the German astronomer Bessel, the system was classed as an astrometric binary, because the companion star, Sirius B, was too faint to be seen. Bessel, who was also a mathematician, determined by calculations that Sirius B existed after observing that the proper of Sirius A (the main star) followed a wavy path in the sky, rather than a uniform path. Sirius can now be studied as a visual binary because, with improving technology and therefore improved telescopes, Sirius B was able to be seen, although not for 20 years after Bessel had correctly predicted its existence.
Black Holes in a binary System ?
The term “binary system” is not used exclusively for star systems, but also for planets, asteroids, and galaxies which rotate around a common center of gravity. However, this is not a trick question; even in star binaries, the companion can be a black hole. An example of this is Cygnus X-1.
The universe is pretty amazing huh?…