标题： TOI-201系统中通过TTVs揭示的7.7年轨道上的凌日巨行星 显示英文标题

标题： A Transiting Giant on a 7.7-Year Orbit Revealed by TTVs in the TOI-201 System

摘要： 我们报告了TOI-201 c的检测和表征，这是温暖木星TOI-201 b的一个长周期凌日伴星。其存在最初是通过TOI-201 b的高振幅凌日时间变化（TTVs）推断出来的，指向一个在$7.7^{+1.0}_{-0.6}$年偏心轨道上的大质量外天体。当TESS观测到TOI-201 c的凌日时，这一预测得到了证实，精确限定了其轨道几何结构。对TTVs、凌日光度测量和档案径向速度的联合拟合得出其质量为$14.2^{+1.0}_{-1.2}$ $M_{\rm Jup}$ ，偏心率为$0.643^{+0.009}_{-0.021}$。行星b和c之间的相互倾角为$2.9^{+4.8}_{-4.4}$度，表明其几乎共面的结构。长期数值积分确认了十亿年时间尺度上的动力学稳定性，并预测TOI-201 b的凌日将在几千年内停止。TOI-201 c位列具有明确特性且周期最长的凌日行星之中。通过TTVs发现，随后确认凌日，这是一种罕见的观测序列，突显了TTVs和光度监测在发现遥远伴星方面的强大能力。TOI-201系统为测试多行星系统中巨行星形成、迁移和长期演化模型提供了宝贵的实验室。 显示英文摘要

摘要： We report the detection and characterization of TOI-201 c, a long-period transiting companion to the warm Jupiter TOI-201 b. Its presence was first inferred from high-amplitude transit timing variations (TTVs) in TOI-201 b, pointing to a massive outer body on a $7.7^{+1.0}_{-0.6}$-year eccentric orbit. This prediction was confirmed when TESS observed a transit of TOI-201 c, precisely constraining its orbital geometry. A joint fit to TTVs, transit photometry, and archival radial velocities yields a mass of $14.2^{+1.0}_{-1.2}$ $M_{\rm Jup}$ and an eccentricity of $0.643^{+0.009}_{-0.021}$. The mutual inclination between planets b and c is $2.9^{+4.8}_{-4.4}$ degrees, indicating a nearly coplanar architecture. Long-term numerical integrations confirm dynamical stability over gigayear timescales and predict that transits of TOI-201 b will cease within a few thousand years. TOI-201 c ranks among the longest-period transiting planets with well-constrained properties. Its detection via TTVs, followed by a confirmed transit, represents a rare observational sequence and highlights the power of TTVs and photometric monitoring to uncover distant companions. The TOI-201 system offers a valuable laboratory for testing models of giant planet formation, migration, and secular evolution in multi-planet systems.