Planet-star interactions with precise transit timing. II. The radial-velocity tides and a tighter constraint on the orbital decay rate in the WASP-18 system
Planet-star interactions with precise transit timing. II. The radial-velocity tides and a tighter constraint on the orbital decay rate in the WASP-18 system
复制标题
行星与恒星的相互作用具有精确的凌日时间。
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
C. Migaszewski
中科院分区：
文献类型：
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作者：
G. Maciejewski;H. Knutson;A. Howard;H. Isaacson;E. Fernández;R. Sisto;C. Migaszewski
从它的发现，WASP-18系统及其在紧密轨道上的大质量凌日行星被确定为研究潮汐行星-恒星相互作用的独特实验室。在对多普勒数据的分析中，其中包括2012年至2018年期间使用HIRES/Pik-I仪器获得的五个新测量值，我们表明可以为宿主星星提取光球跟随行星潮汐势的径向速度信号。它的振幅与平衡潮汐近似的理论预测和在轨道相位曲线中观察到的椭球调制一致。假设一个圆形的轨道，我们细化系统参数使用TESS的光度时间序列。通过新的地面测光观测，我们将凌日计时观测的跨度延长到28年，以探测轨道周期缩短的速率。由于我们没有发现与恒定周期模型的偏离，因此我们得出结论，在95%的置信度下，主星星的修正潮汐质量参数必须大于3.9 × 10 ^6。这一结果与从热对流层的研究中得出的结论一致，预测潮汐耗散的效率要弱1或2个数量级。由于WASP-18系统是探测轨道衰变的主要候选者之一，进一步的定时观测有望推动我们对恒星内部知识的边界。
From its discovery, the WASP-18 system with its massive transiting planet on a tight orbit was identified as a unique laboratory for studies on tidal planet-star interactions. In an analysis of Doppler data, which include five new measurements obtained with the HIRES/Keck-I instrument between 2012 and 2018, we show that the radial velocity signal of the photosphere following the planetary tidal potential can be distilled for the host star. Its amplitude is in agreement with both theoretical predictions of the equilibrium tide approximation and an ellipsoidal modulation observed in an orbital phase curve. Assuming a circular orbit, we refine system parameters using photometric time series from TESS. With a new ground-based photometric observation, we extend the span of transit timing observations to 28 years in order to probe the rate of the orbital period shortening. Since we found no departure from a constant-period model, we conclude that the modified tidal quality parameter of the host star must be greater than 3.9x10^6 with 95% confidence. This result is in line with conclusions drawn from studies of the population of hot Jupiters, predicting that the efficiency of tidal dissipation is 1 or 2 orders of magnitude weaker. As the WASP-18 system is one of the prime candidates for detection of orbital decay, further timing observations are expected to push the boundaries of our knowledge on stellar interiors.