周期性辐照的潮汐锁定行星的大气动力学与变率
Atmospheric dynamics and variability of periodically irradiated tidally locked planets
- University of Toronto（多伦多大学）
- University of Oxford（牛津大学）
- The Pennsylvania State University（宾夕法尼亚州立大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究首次从动力学角度系统研究变化辐照潮汐锁定行星的大气响应，发现共振导致全球驻波和夜面变暖，并识别出11颗具有显著相位曲线调制的候选行星。
AI中文摘要：
随时间变化的恒星加热可能在异步行星上产生新的气候状态，例如永久炎热或寒冷的半球。偏心轨道上的行星、环双星行星以及围绕重力昏暗恒星极轨道运行的行星都会受到变化的辐照，然而变化辐照行星（VIPs）尚未从基本动力学角度进行研究。我们首次对变化辐照的潮汐锁定行星的大气响应进行了广义研究，使用一个受时间依赖辐射平衡驱动的1.5层浅水模型。我们推导了响应的均值、振幅和相位滞后的线性化解析表达式，该响应相当于受迫阻尼谐振子，并在稳态强迫极限下恢复了潮汐锁定行星的既定趋势。当辐照变化与波的时间尺度匹配且阻尼较弱时，由于波自由传播和干涉，会发生共振。共振产生全球驻波模式，从而暂时使夜面变暖。线性和非线性模拟重现了这些结果，并显示热点以强迫频率在经度上振荡，在共振时到达反恒星点。振荡相对于恒星点经度向东或向西，取决于旋转速率和系统的非线性。合成相位曲线带有这种变率的特征，并在共振时因夜面变暖而形状反转。在观测到的系统中，我们发现11颗行星的相位曲线调制至少10%来自变化辐照。偏心、伪同步的巨行星是最有希望的目标，其中HAT-P-2b具有最大的预测调制。
英文摘要：
Time-variable stellar heating may create new climate states, such as permanently hot or cold hemispheres, on asynchronous planets. Planets on eccentric orbits, circumbinary planets and planets on polar orbits around gravity-darkened stars all receive variable irradiation, yet variably irradiated planets (VIPs) have not been studied from a fundamental dynamical perspective. We present the first generalized study of the atmospheric response of variably irradiated tidally locked planets, using a 1.5-layer shallow-water model forced towards a time-dependent radiative equilibrium. We derive linearized analytic expressions for the mean, amplitude and phase lag of the response, which is that of a forced damped harmonic oscillator, and recover the established trends of tidally locked planets in the limit of steady forcing. When the instellation variation and wave timescales match and the damping is weak, a resonance occurs because waves propagate and interfere freely. The resonance produces a global standing wave mode and consequently a temporarily warmer nightside. Linear and nonlinear simulations reproduce these results and show that the hotspot oscillates longitudinally at the forcing frequency and reaches the antistellar point at resonance. The oscillation is eastward or westward of the substellar longitude depending on the rotation rate and the nonlinearity of the system. Synthetic phase curves carry signatures of this variability and invert in shape at resonance because of nightside warming. Among observed systems, we find 11 planets with at least 10% phase curve modulation from variable irradiation. Eccentric, pseudo-synchronous giants are the most promising targets, with HAT-P-2b having the largest predicted modulation.
