Illustration of the triple star system HD 131399, as seen from a planet. The system consists of a close binary pair of low-mass, red stars, separated by about 10 astronomical units (AU), which is in turn in orbit around a more massive, white main-sequence star at a distance of several hundred AU. Astronomers thought they detected a planet around the more massive star, HD 131399 A. However, the so-called planet, dubbed HD 131399 Ab or Scorpion-1b, is now thought to be a background star. This image imagines the supposed planet viewed from a nearby moon. |