系外行星探测。M 矮星 Gliese 581 宜居带中恒星活动伪装成行星。

Exoplanet detection. Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581.

机构信息

Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA. Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802, USA. The Penn State Astrobiology Research Center, The Pennsylvania State University, University Park, PA 16802, USA.

出版信息

Science. 2014 Jul 25;345(6195):440-4. doi: 10.1126/science.1253253. Epub 2014 Jul 3.

DOI:10.1126/science.1253253

PMID:24993348

Abstract

The M dwarf star Gliese 581 is believed to host four planets, including one (GJ 581d) near the habitable zone that could possibly support liquid water on its surface if it is a rocky planet. The detection of another habitable-zone planet--GJ 581g--is disputed, as its significance depends on the eccentricity assumed for d. Analyzing stellar activity using the Hα line, we measure a stellar rotation period of 130 ± 2 days and a correlation for Hα modulation with radial velocity. Correcting for activity greatly diminishes the signal of GJ 581d (to 1.5 standard deviations) while significantly boosting the signals of the other known super-Earth planets. GJ 581d does not exist, but is an artifact of stellar activity which, when incompletely corrected, causes the false detection of planet g.

摘要

G 型矮星 Gliese 581 被认为拥有四颗行星，其中一颗（GJ 581d）位于宜居带附近，如果它是一颗岩石行星，那么其表面可能存在液态水。另一颗位于宜居带的行星——GJ 581g 的存在存在争议，因为其重要性取决于对 d 所假设的偏心率。我们通过 Hα 线分析恒星活动，测量出恒星的自转周期为 130 ± 2 天，并发现 Hα 调制与径向速度之间存在相关性。通过对活动进行校正，大大降低了 GJ 581d 的信号（降至 1.5 个标准差），同时显著增强了其他已知超级地球行星的信号。GJ 581d 并不存在，而是恒星活动的一种假象，如果不完全校正，会导致对 g 行星的错误探测。