Nature. 2016 Jun 30;534(7609):662-6. doi: 10.1038/nature18305. Epub 2016 Jun 20.
Hot Jupiters are giant Jupiter-like exoplanets that orbit their host stars 100 times more closely than Jupiter orbits the Sun. These planets presumably form in the outer part of the primordial disk from which both the central star and surrounding planets are born, then migrate inwards and yet avoid falling into their host star. It is, however, unclear whether this occurs early in the lives of hot Jupiters, when they are still embedded within protoplanetary disks, or later, once multiple planets are formed and interact. Although numerous hot Jupiters have been detected around mature Sun-like stars, their existence has not yet been firmly demonstrated for young stars, whose magnetic activity is so intense that it overshadows the radial velocity signal that close-in giant planets can induce. Here we report that the radial velocities of the young star V830 Tau exhibit a sine wave of period 4.93 days and semi-amplitude 75 metres per second, detected with a false-alarm probability of less than 0.03 per cent, after filtering out the magnetic activity plaguing the spectra. We find that this signal is unrelated to the 2.741-day rotation period of V830 Tau and we attribute it to the presence of a planet of mass 0.77 times that of Jupiter, orbiting at a distance of 0.057 astronomical units from the host star. Our result demonstrates that hot Jupiters can migrate inwards in less than two million years, probably as a result of planet–disk interactions.
热木星是一种巨大的类木星系外行星，其轨道距离宿主恒星比木星绕太阳的距离近 100 倍。这些行星据推测是在原始星盘中形成的，原始星盘是形成中心恒星和周围行星的地方，然后向内迁移，但避免落入宿主恒星。然而，目前尚不清楚这种情况是在热木星的早期生命阶段发生的，当时它们仍然嵌入原行星盘中，还是在形成和相互作用之后的后期发生的。尽管已经在许多类似太阳的成熟恒星周围探测到了大量的热木星，但它们在年轻恒星中的存在尚未得到确凿证明，因为年轻恒星的磁活动非常强烈，以至于掩盖了近距离巨行星可能引起的径向速度信号。在这里，我们报告说，年轻恒星 V830 Tau 的径向速度表现出一个周期为 4.93 天、半振幅为 75 米/秒的正弦波，在过滤掉困扰光谱的磁活动后，其虚假警报概率小于 0.03%。我们发现，这个信号与 V830 Tau 的 2.741 天自转周期无关，我们将其归因于一颗质量为木星的 0.77 倍的行星的存在，它以 0.057 天文单位的距离绕宿主恒星运行。我们的结果表明，热木星可以在不到两百万年内向内迁移，这可能是行星-盘相互作用的结果。
