AI 中文总结
本研究利用SPIRou和NIRPS的观测数据，首次探测到TRAPPIST-1行星系统的组合视向速度信号，验证了其行星质量，并约束了雪线外巨行星的存在，确定了恒星活动周期与磁场上限。
AI 中文摘要
TRAPPIST-1系统以拥有7颗凌日的地球大小系外行星而闻名，该系统已被广泛研究和表征，尤其是通过凌日时间变化（TTVs）来精确测量行星质量。本研究利用作为SPIRou legacy survey（ legacy survey： legacy巡天项目）和NIRPS Guaranteed Time Observation（Guaranteed Time Observation：保障时间观测项目）一部分获取的近红外光谱观测数据，旨在通过该系统的视向速度（RV）测量验证这些质量值。我们的RV分析显示，当前数据的精度不足以单独探测TRAPPIST-1行星，但通过利用TTV分析中行星的相对质量（以TRAPPIST-1 b作为整个系统的代表），我们自信地探测到了行星的组合RV信号（Δln𝒵=7.53，赔率为1860:1）。这是首次恢复出TRAPPIST-1系统的RV信号：我们测得RV半振幅为K_b=3.65⁺⁰·⁷⁸₋₀·⁸³ m s⁻¹，对应行星质量为M_{p,b}=1.31±0.29 M⊕，表明RV测量结果与TTV模型（M_{p,b;TTV}=1.374±0.069 M⊕）一致。此外，NIRPS的RV数据约束了雪线以外巨行星的存在，排除了轨道周期达2.7年的土星质量行星，以及轨道周期达20天的海王星质量天体。通过RV测量，我们确定恒星活动周期为3.22⁺⁰·²²₋₀·²⁰天，其与K2和TESS的测光测量结果一致，证实TRAPPIST-1观测到的~3.3天周期性源于恒星自转。我们还利用SPIRou偏振测量进一步研究恒星活动，对纵向磁场设定了上限（|B_l|<40 G，3σ），该上限与部分晚型快速旋转M型矮星中观测到的弱多极大规模磁场几何结构相符。
英文摘要
The TRAPPIST-1 system is well-known for its seven transiting Earth-sized exoplanets. It has been extensively studied and characterized, notably with transit timing variations (TTVs) to precisely measure the mass of the planets. Using near-infrared spectroscopic observations obtained as part of the SPIRou Legacy Survey and the NIRPS Guaranteed Time Observation programs, we aimed to verify those values through radial velocity (RV) measurements of the system. Our RV analysis reveals that the current data do not have the precision required to individually detect the TRAPPIST-1 planets. However, we confidently detect ($Δ\ln\mathcal{Z}=7.53$, 1860:1 odds) the combined RV signature of the planets by informing their relative masses on the TTV analysis, with TRAPPIST-1 b as a proxy of the whole system. For the first time, the RV signal of the TRAPPIST-1 system is recovered: we find a RV semi-amplitude of $K_b=3.65^{+0.78}_{-0.83}$ m s$^{-1}$ corresponding to a planetary mass of $M_{p,\,b}=1.31\pm0.29$ M$_\oplus$, demonstrating that the RV measurements are consistent with the TTV model ($M_{p,\,b;\,\text{TTV}}=1.374\pm0.069$ M$_\oplus$). Additionally, the NIRPS RVs constrain the presence of giant planets beyond the snow line, excluding Saturn-mass planets out to 2.7-yr orbits and Neptune-mass objects out to 20 d. Through RV, we determined the stellar activity period to be of $3.22^{+0.22}_{-0.20}$ d. Its agreement with photometric measurements (K2 and TESS) confirms stellar rotation as the origin of the $\sim3.3$-d periodicity observed for TRAPPIST-1. We further investigated stellar activity with SPIRou polarimetric measurements, placing an upper limit on the longitudinal field ($|B_l|<40$ G, $3σ$). This limit is compatible with a weak multipolar large-scale magnetic geometry, as observed in some of the later-type rapidly rotating M dwarfs.
CommentsAccepted for publication in Astronomy & Astrophysics
