TNG的GAPS计划XLIII：围绕活跃M矮星TOI-5375的一颗大质量褐矮星
The GAPS programme at TNG XLIII. A massive brown dwarf orbiting the active M dwarf TOI-5375
AI总结：
本研究通过TESS和HARPS-N数据，发现围绕M矮星TOI-5375的一颗大质量褐矮星，其轨道周期为1.721564天，质量为77木星质量，并指出恒星旋转接近同步。
摘要：
背景：围绕活跃低质量恒星的大质量亚恒星伴星是罕见的。然而，它们为研究亚恒星天体形成和演化的主要机制提供了绝佳的机会。目标：我们旨在揭示TESS空间任务在活跃M矮星TOI-5375上观测到的凌星信号的物理本质。方法：我们分析了可用的TESS光度数据以及高分辨率（R ~ 115000）的HARPS-N光谱。我们将这些数据结合起来，以表征恒星TOI-5375，并从光变曲线数据中区分与恒星活动相关的信号和伴星凌星信号。我们进行了MCMC分析以推导轨道解，并应用最先进的高斯过程回归来处理恒星活动信号。结果：我们揭示了在褐矮星/极低质量恒星边界处存在一个围绕TOI-5375恒星运行的伴星。最佳拟合模型对应一个轨道周期为1.721564 ± 10^-6天，质量为77 ± 8木星质量，半径为0.99 ± 0.16木星半径的伴星。结论：我们得出宿主恒星的旋转周期为1.9692 ± 0.0004天，并得出结论，该恒星非常接近其旋转与伴星轨道周期的同步。
英文摘要：
Context. Massive substellar companions orbiting active low-mass stars are rare. They, however, offer an excellent opportunity to study the main mechanisms involved in the formation and evolution of substellar objects. Aims. We aim to unravel the physical nature of the transit signal observed by the TESS space mission on the active M dwarf TOI-5375. Methods. We analysed the available TESS photometric data as well as high-resolution (R $\sim$ 115000) HARPS-N spectra. We combined these data to characterise the star TOI-5375 and to disentangle signals related to stellar activity from the companion transit signal in the light-curve data. We ran an MCMC analysis to derive the orbital solution and apply state-of-the-art Gaussian process regression to deal with the stellar activity signal. Results. We reveal the presence of a companion in the brown dwarf / very-low-mass star boundary orbiting around the star TOI-5375. The best-fit model corresponds to a companion with an orbital period of 1.721564 $\pm$ 10$^{\rm -6}$ d, a mass of 77 $\pm$ 8 $M_{\rm J}$ and a radius of 0.99 $\pm$ 0.16 $R_{\rm J}$. Conclusions. We derive a rotation period for the host star of 1.9692 $\pm$ 0.0004 d, and we conclude that the star is very close to synchronising its rotation with the orbital period of the companion.
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