模拟天龙座γ的准周期径向速度变化
Modeling the quasiperiodic radial velocity variations of gamma Draconis
摘要：
K5 III型恒星天龙γ在2003-2011年期间表现出与10.7木星质量行星一致的径向速度（RV）变化。2011年之后，周期信号衰减，然后以相移重新出现。Hatzes等人（2018）认为伽马Dra的RV变化可能来自振荡对流模式，但不符合数学模型。在这里，我们评估是否一个准周期高斯过程（GP）--适当的时候，与有限的生命周期跟踪潜在的周期性斑点-可以解释的RV。我们发现，只有一个准周期信号的模型是不够的：我们需要第二个组件，以适应数据。最佳拟合模型具有准周期振荡，P1 = 705天，P2 = 15天。705天信号可能是由磁场活动引起的。15天的期限需要进一步调查。
英文摘要：
gamma Draconis, a K5III star, showed radial velocity (RV) variations consistent with a 10.7 Jupiter mass planet from 2003-2011. After 2011, the periodic signal decayed, then reappeared with a phase shift. Hatzes et al. (2018) suggested that gamma Dra's RV variations could come from oscillatory convective modes, but did not fit a mathematical model. Here we assess whether a quasi-periodic Gaussian process (GP)---appropriate when spots with finite lifetimes trace underlying periodicity---can explain the RVs. We find that a model with only one quasiperiodic signal is not adequate: we require a second component to fit the data. The best-fit model has quasi-periodic oscillations with P1 = 705 days and P2 = 15 days. The 705-day signal may be caused by magnetic activity. The 15-day period requires further investigation.
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