... binary stars can have solar systems?
A solar system in which the planets orbit two stars sounds like pure science fiction. But binary stars are said to exist. Is this true?
Not nearly all stars travel alone through space. At least half of all stars in the night sky have companions and belong to a system of two or more stars, which gravity maintains in permanent orbits around a common centre of gravity.
Within a distance of 20 light years from the Sun, you will find 16 binary stars and three triple stars. The Sun’s closest neighbour, Alpha Centauri, is a system of 3 stars, consisting of the 2 stars of Alpha Centrauri A and B in close orbit around each other and the more remote and weaker Proxima Centauri.
Binary stars are formed in the same cloud of gas and dust. So, they consist of the exact same elements and are the same age. But sometimes they are born with different masses, meaning that they develop differently and do not live for the same period of time. The star with the largest mass will die first.
Some scientists even assume that all stars, including our own Sun, are born as binary stars. The Sun’s hypothetical twin is called Nemesis, and billions of years ago, it entered a path that sent it far away from the Solar System. According to this theory, Nemesis might still exist somewhere in the Milky Way. The twin is probably a brown dwarf – i.e. a small, cold star that will never be warm enough to start a fusion process.
In the Kepler 47 star system 3,400 light years from the Sun, at least three planets are orbiting a spectroscopic binary star.