PHOTOMETRIC AND SPECTRAL SIGNATURES OF THREE-DIMENSIONAL MODELS OF TRANSITING GIANT EXOPLANETS
PHOTOMETRIC AND SPECTRAL SIGNATURES OF THREE-DIMENSIONAL MODELS OF TRANSITING GIANT EXOPLANETS
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凌日巨系外行星三维模型的光度和光谱特征
DOI：
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发表时间：
2010
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通讯作者：
K. Menou
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作者：
Adam Burrows;E. Rauscher;David S. Spiegel;K. Menou
使用三维大气环流模型，我们创建一个代表性的过境巨型系外行星，HD 209458 b的动力学模型大气。我们后处理这些大气层的不透明度代码，以获得过境半径光谱在主过境。使用光谱大气代码，我们整合了在不同的轨道相位观察者看到的行星的表面，并计算光变曲线作为波长的函数和不同的光度带。这项研究的产品是一个零偏心率的巨行星的过境光谱和它的光变曲线的相位变化的一般预测。我们发现，对于这些模型的时间变化的所有数量和过境半径的入口/出口对比度是小的（<1.0%）。此外，我们确定的昼夜对比度和相对于星历表的亮度峰值的相移是光度带的函数。J、H和K频带偏移最多，而IRAC频带偏移最少。因此，我们验证了由于赤道风的行星“热点”的顺风移动的幅度是强烈的波长依赖性。光变曲线的相位和波长依赖性，以及相关的日/夜对比度，可以用来限制被照射的巨行星的循环制度，并探测热木星大气的不同压力水平。我们认为，虽然我们的计算集中在HD 209458 b的模型，类似的计算其他过境热彗星在低偏心率轨道应产生过境光谱和光变曲线的类似性质。
Using a three-dimensional general circulation model, we create dynamical model atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small (<1.0%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The J, H, and K bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary “hot spot” due to equatorial winds is strongly wavelength dependent. The phase and wavelength dependence of light curves, as well as the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter atmosphere. We posit that though our calculations focus on models of HD 209458b, similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.