Free Astronomy Magazine September-October 2016

SPACE CHRONICLES Kevin Wagner, who is a PhD student at the University of Arizona, identified the planet among hundreds of candidate planets and led the follow-up observations to verify its nature. The planet also marks the first discovery of an exoplan- et made with the SPHERE instrument on the VLT. SPHERE is sensitive to infra- red light, allowing it to de- tect the heat signatures of young planets, along with sophisticated features cor- recting for atmospheric disturbances and blocking out the otherwise blinding light of their host stars. Although repeated and long-term observations will be need- ed to precisely determine the plan- et's trajectory among its host stars, T his video shows the orbit of the plan- et in the triple- star system HD 131399. Two of the stars are close together and the third, brighter com- ponent is or- bited by a gas giant planet named HD 131399Ab. [ESO/L. Calçada/ M. Kornmesser] T his graphic shows the orbit of the planet in the HD 131399 system (red line) and the orbits of the stars (blue lines). The planet orbits the brightest star in the system, HD 131399A. [ESO] observations and simulations seem to suggest the following scenario: the brightest star is estimated to be eighty percent more massive than the Sun and dubbed HD 131399A, which itself is orbited by the less massive stars, B and C, at about 300 au (one au, or astronomical unit, equals the average distance be- tween the Earth and the Sun). All the while, B and C twirl around each other like a spinning dumb-