Three giant planets were discovered orbiting a pair of stellar ‘twins’ – a binary stellar system with identical temperature and mass (HD13313 A and B). Incidentally, both stars are very similar to the Sun, except for their age. Scientists estimate its age at 9.5 billion years, compared to 4.6 billion years for our Sun. One giant planet of 2.5 Jupiter masses orbit one star, and two planets of 1.4 and 0.6 Jupiter masses orbit the other star.

Exoplanets in binary stars were discovered before, but the HD13313 pair is the most closely separated ‘twin’ pair with detected planets: the distance between stars is only 360 AU*.  This system of two stars and three planets will serve as an important benchmark for understanding planet formation, especially in binary systems,

* AU = Astronomical Unit, distance between the Sun and the Earth

Artist’s concept of giant planets orbiting in double-star system. Image credit: NASA / JPL-Caltech / T. Pyle.

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