AI 中文总结
本研究针对RY Lup的径向速度变化，通过VLT/ESPRESSO数据等分析，探讨其源于双星或恒星星斑的可能性，发现双星假说与观测部分契合但存矛盾，星斑假说无法单独解释，建议未来结合监测明确本质。
AI 中文摘要
恒星多重性是产生原行星盘亚结构的可能原因，因为近距离光谱伴星的潮汐力可刻出间隙并塑造盘的结构。然而，在年轻活跃系统中，径向速度（RV）信号常因恒星活动变得复杂。我们研究RY Lup，这是一颗拥有约60天文单位空腔盘的经典T Tauri星，盖亚天体测量和VLT/SPHERE成像研究暗示存在未被发现的伴星。利用高分辨率VLT/ESPRESSO光谱和最小二乘反卷积（LSD）技术，我们分析了327天内的RV变化，检测到具有约3.75天周期信号的显著线轮廓变化，与之前的测光估计一致。这些变化与约0.04天文单位的近距离双星系统及约0.6的质量比相符。结合RV数据和ALMA动力学质量估计（使用13CO和18CO）的分析显示，该系统高度错位：近面向双星倾角i≈13度，与内盘（i≈50度）和外盘（i≈70度）均错位，推导的轨道间距与内盘大小兼容，VLTI/GRAVITY测得内盘半径a=0.12天文单位，表明盘结构高度扭曲。不过，短轨道周期与推导的偏心率（e≈0.23）存在矛盾。为探索替代解释，我们评估了恒星星斑对RV信号的影响。虽然LSD形变可通过不同冷星斑构型建模，但恢复的v sin i值存在15%的离散，且缺乏显著周期信号，这表明仅星斑无法解释观测到的变化。由于两种假说均未被排除，我们建议未来结合RV和干涉测量监测以明确光谱变化的本质。
英文摘要
Stellar multiplicity is a possible cause for creating protoplanetary disc substructures, as tidal forces from a close-in spectroscopic companion can carve out gaps and shape disc architecture. However, in young, active systems, the radial velocity (RV) signatures are often complicated by stellar activity. We investigate RY Lup, a classical T Tauri star hosting a disc with a ~60 au cavity, where studies with Gaia astrometry and VLT/SPHERE imaging hinted at an unseen companion. Using high-resolution VLT/ESPRESSO spectra and the least-squares deconvolution (LSD) technique, we analyse RV variations over 327 days. We detect significant line profile variations with a periodic signal of ~3.75 days, aligning with prior photometric estimates. The variations are compatible with a close-in binary system at ~0.04 au and a mass ratio of q ~ 0.6. Combined analysis of RV data and ALMA dynamical mass estimates, using 13CO and 18CO, reveals a highly misaligned system. The nearly face-on binary i ~ 13 deg is misaligned to both the inner and outer discs i ~ 50 deg and ~70 deg, respectively. The derived orbital separation is compatible with the inner disc size, with the inner rim at a = 0.12 au, measured from VLTI/GRAVITY, which suggests a highly warped disc structure. Nonetheless, the short orbital period conflicts with the derived eccentricity (e ~ 0.23). To explore alternative explanations, we assess the impact of stellar spots on RV signals. While the LSD deformations can be modelled by different cool spot configurations, a 15% dispersion in retrieved v sin i values -- coupled with the lack of a significant periodic signal -- suggests that spots alone cannot explain the observed variability. As neither hypothesis is ruled out, we recommend future combined RV and interferometric monitoring to clarify the nature of the spectroscopic variability.
CommentsAccepted by A&A
