Title: Stellar-activity analysis of the nearby M dwarf GJ 526. Multi-dimensional Gaussian-process modelling of RV, FWHM and S-index Show Chinese title

Title: 附近的M型矮星GJ 526的恒星活动分析。 RV、FWHM和S指数的多维高斯过程建模

Abstract: M dwarfs are the most abundant stars in the Galaxy, and their low masses make them natural favourites for exoplanet radial-velocity (RV) searches. Nevertheless, these stars often demonstrate strong stellar activity that is yet to be fully understood. We use high-precision ESPRESSO, HIRES, and HARPS spectroscopy to perform a stellar-activity analysis on the nearby early M dwarf GJ 526 ($d=5.4$ pc). We carry out joint modelling of: (i) stellar rotation in RV, FWHM, and Mount Wilson S-index through Gaussian processes, (ii) long-term trends in these three physical quantities, (iii) RV planetary signals. We constrain the stellar-rotation period to $P_\text{rot}=48.7\pm 0.3$ d, and discover a weak sinusoidal signature in RV, FWHM and S-index of period $P_\text{cyc}=1680^{+50}_{-40}$ d. We propose phase-space trajectories between RV and activity indicators as a novel means to visualise and interpret stellar activity. Current evidence does not support planetary companions of GJ 526. Show Chinese abstract

Abstract: M型矮星是银河系中最多的恒星，它们的低质量使它们成为系外行星径向速度（RV）搜索的天然首选。 然而，这些恒星通常表现出强烈的恒星活动，这仍未被完全理解。 我们使用高精度的ESPRESSO、HIRES和HARPS光谱学对邻近的早期M型矮星GJ 526（$d=5.4$pc）进行恒星活动分析。 我们对以下内容进行联合建模：（i）通过高斯过程在RV、FWHM和威尔逊山S指数中的恒星自转，（ii）这三个物理量的长期趋势，（iii）RV行星信号。 我们将恒星自转周期限制为$P_\text{rot}=48.7\pm 0.3$d，并发现RV、FWHM和S指数中存在一个弱的正弦特征，周期为$P_\text{cyc}=1680^{+50}_{-40}$d。我们提出RV与活动指标之间的相空间轨迹作为一种新的方法来可视化和解释恒星活动。 目前的证据不支持GJ 526有行星伴星。