论文标题
HD 189733b的氦气吸收可变的更多证据
More Evidence for Variable Helium Absorption from HD 189733b
论文作者
论文摘要
我们提出了新的Keck/NirSpec观察到HD 189733B高清大气中亚稳态氦吸收的新观察，这是一种旋转附近中度活跃恒星的热木星。我们在[-20，20] km/s速度范围内集成的平均氦境深度为0.420 \ pm 0.013 $％。将这种测量与具有不同仪器的八个先前发表的过境观测值进行比较，我们发现我们的深度比三个狂热者的平均值低32％（9 $σ$），但仅比五个Giano Transits的平均值16％（4.4 $σ$）低。我们对流出进行了1D流体动力学模拟，发现XUV的变异性在33％的阶段 - 常见于该星际 - can-can将氦的吸收深度降低60％。我们得出的结论是，恒星XUV通量的变化可以解释氦吸收的观察性变异性。 3D模型对于探索其他可变性来源是必要的，例如剪切不稳定性和变化的恒星风条件。
We present a new Keck/NIRSPEC observation of metastable helium absorption from the upper atmosphere of HD 189733b, a hot Jupiter orbiting a nearby moderately active star. We measure an average helium transit depth of $0.420 \pm 0.013$% integrated over the [-20, 20] km/s velocity range. Comparing this measurement to eight previously published transit observations with different instruments, we find that our depth is 32% (9$σ$) lower than the average of the three CARMENES transits, but only 16% (4.4$σ$) lower than the average of the five GIANO transits. We perform 1D hydrodynamical simulations of the outflow, and find that XUV variability on the order of 33%--common for this star--can change the helium absorption depth by 60%. We conclude that changes in stellar XUV flux can explain the observational variability in helium absorption. 3D models are necessary to explore other sources of variability, such as shear instability and changing stellar wind conditions.
