Direct Imaging of Multiple Planets Orbiting the Star HR 8799

摘要

Direct imaging of exoplanetary systems is a powerful technique that canreveal Jupiter-like planets in wide orbits, can enable detailedcharacterization of planetary atmospheres, and is a key step towards imagingEarth-like planets. Imaging detections are challenging due to the combinedeffect of small angular separation and large luminosity contrast between aplanet and its host star. High-contrast observations with the Keck and Geminitelescopes have revealed three planets orbiting the star HR 8799, withprojected separations of 24, 38, and 68 astronomical units. Multi-epoch datashow counter-clockwise orbital motion for all three imaged planets. The lowluminosity of the companions and the estimated age of the system implyplanetary masses between 5 and 13 times that of Jupiter. This system resemblesa scaled-up version of the outer portion of our Solar System.