We report Spitzer/IRAC photometry of the transiting giant exoplanet HAT-P-1b during its secondary eclipse. This planet lies near the postulated boundary between the pM and pL-class of hot Jupiters, and is important as a test of models for temperature inversions in hot Jupiter atmospheres. We derive eclipse depths for HAT-P-1b, in units of the stellar flux, that are: 0.080% ± 0.008% [3.6 μm], 0.135% ± 0.022% [4.5 μm], 0.203% ± 0.031% [5.8 μm], and 0.238% ± 0.040% [8.0 μm]. These values are best fit using an atmosphere with a modest temperature inversion, intermediate between the archetype inverted atmosphere (HD?209458b) and a model without an inversion. The observations also suggest that this planet is radiating a large fraction of the available stellar irradiance on its dayside, with little available for redistribution by circulation. This planet has sometimes been speculated to be inflated by tidal dissipation, based on its large radius in discovery observations, and on a non-zero orbital eccentricity allowed by the radial velocity data. The timing of the secondary eclipse is very sensitive to orbital eccentricity, and we find that the central phase of the eclipse is 0.4999 ± 0.0005. The difference between the expected and observed phase indicates that the orbit is close to circular, with a 3σ limit of |e cos ω| 0.002.
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机译：我们报道了正在过渡的巨型系外行星HAT-P-1b在其次蚀期间的Spitzer / IRAC光度法。这颗行星位于热木星的pM和pL级之间的假定边界附近，对于测试热木星大气中的温度反演模型非常重要。我们以恒星通量为单位推导HAT-P-1b的月食深度，即：0.080％±0.008％[3.6μm]，0.135％±0.022％[4.5μm]，0.203％±0.031％[5.8μm] ，以及0.238％±0.040％[8.0μm]。这些值最适合在温度反转适中，原型反转大气（HD？209458b）与无反转模型之间的情况下使用。观测结果还表明，这颗行星在其白天辐射了大部分可用的恒星辐照度，几乎没有可通过循环再分布的辐照度。基于发现观测中的大半径以及径向速度数据允许的非零轨道偏心率，有时已推测该行星因潮汐耗散而膨胀。次食的时机对轨道偏心率非常敏感，我们发现日食的中心相位为0.4999±0.0005。预期相位与观测相位之间的差异表明轨道接近圆形，其3σ极限为| e cosω|。 <0.002。
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