Our nearest neighbor, Proxima Centauri, hosts a temperate terrestrial planet. We detected in radial velocities evidence of a possible second planet with minimum mass m c sin i c = 5.8 ± 1.9M ⊕ and orbital period P c = 5.21 - 0.22 + 0.26 years. The analysis of photometric data and spectro-scopic activity diagnostics does not explain the signal in terms of a stellar activity cycle, but follow-up is required in the coming years for confirming its planetary origin. We show that the existence of the planet can be ascertained, and its true mass can be determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c could become a prime target for follow-up and characterization with next-generation direct imaging instrumentation due to the large maximum angular separation of ~1 arc second from the parent star. The candidate planet represents a challenge for the models of super-Earth formation and evolution.

中文翻译：

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一个低质量的行星候选者，绕着半人马座Proxima绕1.5 AU旋转。

我们最近的邻居Proxima Centauri拥有一个温带的地球。我们在径向速度上发现了可能的第二颗行星，其最小质量mc sin ic = 5.8±1.9M⊕，轨道周期P c = 5.21-0.22 + 0.26年。光度数据分析和光谱活动诊断不能以恒星活动周期来解释该信号，但在未来几年中需要进行后续行动以确认其行星起源。我们证明，通过结合盖亚天文测量法和径向速度，可以确定行星的存在，并可以高精度确定其真实质量。Proxima c可能成为下一代直接成像仪器进行跟踪和表征的主要目标，因为它与母恒星之间的最大最大角度间隔约为1弧秒。