发表机构
Institut Trottier de recherche sur les exoplanètes, Département de Physique, Université de Montréal; Observatoire du Mont-Mégantic; Univ. Grenoble Alpes, CNRS, IPAG; Department of Physics & Astronomy, McMaster University; Osservatorio Astrofisico di Torino; Center for Space and Habitability, University of Bern; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP; Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto; Observatoire de Genève, Département d’Astronomie, Université de Genève; Instituto de Astrofísica de Canarias (IAC); Departamento de Astrofísica, Universidad de La Laguna (ULL); Centro de Astrobiología (CAB), CSIC-INTA（蒙特利尔大学特罗蒂尔系外行星研究所物理系; 梅格尼克天文台; 格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，IPAG实验室; 麦克马斯特大学物理与天文学系; 都灵天文台; 伯尔尼大学太空宜居性中心; 波尔图大学空间与天体物理研究所CAUP; 波尔图大学理学院物理与天文学系; 日内瓦大学天文学系日内瓦天文台; 加那利群岛天体物理研究所; 拉帕卢纳大学天体物理学系; 西班牙国家航空航天技术研究所-西班牙国家科学研究委员会天体生物学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用ESPRESSO等设备8年径向速度数据，结合多维高斯过程，精确测定K2-3系统三颗温带亚海王星质量，并探讨其组成与JWST观测前景。
AI 中文摘要
K2-3系统是最独特的行星系统之一，因为它拥有三颗按半径递减顺序排列的凌星亚海王星，横跨半径谷。此外，两颗外行星本质上是温带的，使得该系统成为研究小型潜在宜居世界的性质与形成的理想实验室。我们展示了在ESPRESSO-GTO计划期间获得的新的径向速度数据，并将其添加到档案中的HARPS、HARPS-N和HIRES数据中，总时间跨度为8年。这一组合数据集显著提高了K2-3行星的质量测量精度。我们使用逐行算法分析光谱数据。我们将该时间序列与多维高斯过程框架相结合，以将40.5天的恒星自转信号与开普勒信号分离。我们测试了使用两种活动指标的模型，以确保恢复的行星半振幅不受活动指标选择的影响。多维高斯过程框架，无论使用哪种活动指标，均得出以下质量：Mb=6.61±0.47M⊕；Mc=2.23±0.68M⊕；Md=2.12±1.27M⊕。与先前工作相比，我们对K2-3b的探测显著性提高了两倍，K2-3c的质量略有下降，现在我们获得了K2-3d的边缘探测。行星在质量-半径图中的位置表明K2-3b和K2-3c可能具有富H/He或富挥发分的组成，而K2-3d的性质尚不明确。一个前向大气模型表明，使用JWST的单次访问即可区分H/He-rich大气与水世界情景。该数据集展示了ESPRESSO探测亚米每秒径向速度信号以发现温带系外行星的能力。
英文摘要
The K2-3 system is one of the most unique planetary systems as it features three transiting sub-Neptunes in decreasing order of radii, spanning the radius valley. In addition to that, the two outer planets are temperate in nature making this system a perfect laboratory for investigating the nature and formation of small potentially habitable worlds. We present new radial velocity data obtained during the ESPRESSO-GTO programme to add to the archival HARPS, HARPS-N and HIRES data for a total time span of 8 years. This combined dataset significantly improves the masses of the K2-3 planets. We analyse the spectroscopic data with the line-by-line algorithm. We coupled this timeseries with a multi-dimensional Gaussian process framework to disentangle the 40.5-days stellar rotation from the Keplerian signals. We tested models using two activity indicators to ensure the retrieved semi-amplitudes of the planets are not biased by the choice of activity indicator. The multi-dimensional Gaussian process framework, with either activity indicator, yields the following masses: Mb=6.61+/-0.47Me; Mc=2.23+/-0.68Me; Md=2.12+/-1.27Me. Compared to previous works, our detection significance of K2-3b has increased by a factor of two, the mass of K2-3c has slightly decreased and we now have a marginal detection for K2-3d. The positions of the planets in the mass-radius diagram suggest either a H/He-rich or volatile-rich composition for both K2-3b and c, while the nature of K2-3d is ambiguous. A forward atmospheric model suggests that a single visit with JWST can distinguish between a H/He-rich atmosphere from a water-world scenario. This dataset exemplifies the capability of ESPRESSO to detect sub-metre-per-second radial velocity signals for the detection of temperate exoplanets.
Comments10 pages, 5 figures, 3 tables. Submitted to A&A Letters. Abstract shortened to fit ArXiv character limitations
