Kalas Paul, Graham James R, Chiang Eugene, Fitzgerald Michael P, Clampin Mark, Kite Edwin S, Stapelfeldt Karl, Marois Christian, Krist John
Astronomy Department, University of California, Berkeley, CA 94720, USA.
Science. 2008 Nov 28;322(5906):1345-8. doi: 10.1126/science.1166609. Epub 2008 Nov 13.
Fomalhaut, a bright star 7.7 parsecs (25 light-years) from Earth, harbors a belt of cold dust with a structure consistent with gravitational sculpting by an orbiting planet. Here, we present optical observations of an exoplanet candidate, Fomalhaut b. Fomalhaut b lies about 119 astronomical units (AU) from the star and 18 AU of the dust belt, matching predictions of its location. Hubble Space Telescope observations separated by 1.73 years reveal counterclockwise orbital motion. Dynamical models of the interaction between the planet and the belt indicate that the planet's mass is at most three times that of Jupiter; a higher mass would lead to gravitational disruption of the belt, matching predictions of its location. The flux detected at 0.8 mum is also consistent with that of a planet with mass no greater than a few times that of Jupiter. The brightness at 0.6 mum and the lack of detection at longer wavelengths suggest that the detected flux may include starlight reflected off a circumplanetary disk, with dimension comparable to the orbits of the Galilean satellites. We also observe variability of unknown origin at 0.6 mum.
北落师门是一颗距离地球7.7秒差距（25光年）的明亮恒星，它拥有一条由寒冷尘埃构成的带，其结构与一颗轨道行星的引力塑造作用相一致。在此，我们展示了对一颗系外行星候选体——北落师门b的光学观测。北落师门b距离恒星约119天文单位（AU），距离尘埃带18天文单位，与其位置的预测相符。间隔1.73年的哈勃太空望远镜观测揭示了其逆时针轨道运动。行星与尘埃带相互作用的动力学模型表明，该行星的质量至多为木星质量的三倍；质量更高会导致尘埃带受到引力破坏，这与对其位置的预测相符。在0.8微米处检测到的通量也与一颗质量不超过木星质量几倍的行星相符。在0.6微米处的亮度以及在更长波长处未检测到信号表明，检测到的通量可能包括从一个环行星盘反射的星光，该环行星盘的尺寸与伽利略卫星的轨道相当。我们还在0.6微米处观测到了来源不明的变异性。
