Ultra-hot Jupiters with equilibrium temperatures greater than 2000 K are uniquely interesting targets as they provide us crucial insights into how atmospheres behave under extreme conditions. This class of giant planets receives intense radiation from their host star and usually has strongly irradiated and highly inflated atmospheres. At such a high temperature, cloud formation is expected to be suppressed and thermal dissociation of water vapor could occur. We observed the ultra-hot Jupiter WASP-76b with seven transits and five eclipses using the Hubble Space Telescope and the Spitzer Space Telescope (Spitzer) for a comprehensive study of its atmospheric chemical and physical processes. We detected TiO and H₂O absorption in the optical and near-infrared transit spectrum. Additional absorption by a number of neutral and ionized heavy metals like Fe, Ni, Ti, and SiO help explain the short-wavelength transit spectrum. The secondary eclipse spectrum shows muted water feature but a strong CO emission feature in Spitzer’s 4.5 μm band indicating an inverted temperature pressure profile. We analyzed both the transit and eclipse spectra with a combination of self-consistent PHOENIX models and atmospheric retrieval. Both spectra were well fitted by the self-consistent PHOENIX forward atmosphere model in chemical and radiative equilibrium at solar metallicity, adding to the growing evidence that both TiO/VO and NUV heavy metals opacity are prominent NUV-optical opacity sources in the stratospheres of ultra-hot Jupiters.

平衡温度高于 2000 K 的超热木星是独特有趣的目标，因为它们为我们提供了关于极端条件下大气行为的重要见解。这类巨行星从它们的主星接收强烈的辐射，通常有强烈的辐射和高度膨胀的大气层。在如此高的温度下，预计云的形成会受到抑制，并且可能会发生水蒸气的热分解。我们使用哈勃太空望远镜和斯皮策太空望远镜 (Spitzer) 观察了具有 7 次凌日和 5 次日食的超热木星 WASP-76b，以全面研究其大气化学和物理过程。我们检测到 TiO 和 H ₂光学和近红外传输光谱中的 O 吸收。许多中性和电离重金属（如 Fe、Ni、Ti 和 SiO）的额外吸收有助于解释短波长传输光谱。二次日食光谱显示出柔和的水特征，但在斯皮策的 4.5 μ m 波段中具有强烈的 CO 排放特征，表明温度压力剖面反转。我们结合自洽 PHOENIX 模型和大气反演分析了凌日和日食光谱。两个光谱都被自洽的 PHOENIX 前向大气模型在太阳金属丰度的化学和辐射平衡中很好地拟合，增加了越来越多的证据，即 TiO/VO 和 NUV 重金属不透明度都是超高温平流层中突出的 NUV 光学不透明度源。 -热木星。