Institut für Astrophysik, Georg-August-UniversitÄt, 37077 Göttingen, Germany.
School of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK.
Science. 2020 Jun 26;368(6498):1477-1481. doi: 10.1126/science.aaz0795. Epub 2020 Jun 25.
The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of super-Earth exoplanets orbiting the nearby red dwarf star GJ 887. The two planets have orbital periods of 9.3 and 21.8 days. Assuming an Earth-like albedo, the equilibrium temperature of the 21.8-day planet is ~350 kelvin. The planets are interior to, but close to the inner edge of, the liquid-water habitable zone. We also detect an unconfirmed signal with a period of ~50 days, which could correspond to a third super-Earth in a more temperate orbit. Our observations show that GJ 887 has photometric variability below 500 parts per million, which is unusually quiet for a red dwarf.
最接近太阳的系外行星为我们提供了研究太阳系外行星的绝佳机会。我们利用径向速度测量法发现了一个由围绕附近红矮星 GJ 887 运行的超地球系外行星组成的紧凑多行星系统。其中两颗行星的轨道周期分别为 9.3 天和 21.8 天。假设具有类似地球的反照率,21.8 天周期行星的平衡温度约为 350 开尔文。这些行星位于液态水可居住区域内,但靠近内边缘。我们还探测到一个未经证实的约 50 天周期信号,它可能对应于一个位于更温和轨道上的第三颗超地球行星。我们的观测表明,GJ 887 的光度变化低于 500 百万分之一,这对于红矮星来说非常安静。