标题： TESS中候选单个晚期M矮星的自转周期 显示英文标题

标题： Rotation Periods of Candidate Single Late-M Dwarfs in TESS

摘要： 最近的研究表明，晚期M型星和棕矮星的角动量演化与较热恒星的已知自转减速演化不同。 在太阳邻域对这些天体的自转周期分布进行表征，有助于阐明氢燃烧极限上方、处于以及下方的这种演化路径。 在本文中，我们研究了399个候选单颗晚期M型矮星，其$G - G_{RP} \geq 1.4$ mag（$\gtrsim$M6）。利用TESS光曲线进行研究。 为了确定自转周期，我们采用Lomb-Scargle周期图提供周期的初步估计，然后使用高斯过程方法进行细化，并在有多个观测时段数据时要求多时段确认。 我们发现了133个自转周期，范围从2小时到6天，振幅在0.08%到2.71%之间。 我们发现晚期M型星的观测变异性比例随着可用TESS时段数量的增加而上升，接近约50%的明显上限。 这可能反映了由观测几何条件决定的检测极限，并支持了由黑子引起的变异性在晚期M型星和棕矮星群体中很常见的观点。 在与之前发表的晚期M型星自转周期比较中，我们得到了一致的结果，确认或更新了31个周期。 我们的发现使已知的自转周期小于1天的晚期M型星数量增加了76%。 结合已发表的更广泛光谱类型自转周期，我们发现自转周期的下限从早期M型星的5小时下降到L、T和Y型矮星的1小时。 显示英文摘要

摘要： Recent studies suggest that the angular momentum evolution of late-M and brown dwarfs differs from the well-known spin-down evolution of hotter stars. Characterizing the distribution of rotation periods of these objects in the solar neighborhood can help elucidate this evolutionary pathway just above, at, and below the hydrogen burning limit. In this paper, we examine 399 candidate single late-M dwarfs with $G - G_{RP} \geq 1.4$ mag ($\gtrsim$M6) using TESS light curves. To determine rotation periods, we employed Lomb-Scargle Periodograms to provide a first estimate of the period, then refined them with a Gaussian Process approach, requiring multi-sector confirmation when available. We found 133 rotation periods, ranging from 2 hours to 6 days, and amplitudes between 0.08% and 2.71%. We find that the observed variability fraction in late-M dwarfs rises with the number of available TESS sectors, approaching an apparent ceiling of ~50%. This likely reflects a detection limit determined by viewing geometry and supports the idea that spot-induced variability is common across the late-M and brown dwarf population. In our comparison with previously published late-M dwarf rotation periods reported, we found consistent results, confirming or updating 31 periods. Our findings expand the number of previously known late-M dwarf periods under 1 day by 76%. Combined with published rotation periods for a broader range of spectral types, we find a lower envelope on the rotation period decreasing from 5 hours at early-M dwarfs to 1 hour at L, T, and Y dwarfs.