SO2, silicate clouds, but no CH4 detected in a warm Neptune.
SO2, silicate clouds, but no CH4 detected in a warm Neptune.
复制标题
SO2、硅酸盐云，但在温暖的海王星中未检测到 CH4。
DOI：
10.1038/s41586-023-06849-0
复制
发表时间：
2024
期刊：
影响因子：
64.8
通讯作者：
Dyrek A
中科院分区：
文献类型：
--
作者：
Dyrek A
WASP-107 b是一颗温暖的凌日行星，质量为30.5 M，半径为10.94 RJ 1，2，其大气层正在侵蚀3。先前的观测显示，在WASP-107 b的大气层中有水蒸气和厚的高空冷凝层的证据4，5。最近，在一颗土星质量的热行星（约1,200 K）的大气中，通过透射光谱在4.05 µm附近检测到了光化学产生的二氧化硫（SO2）6，7，但在低于1,000 K的温度下，硫被预测会优先形成硫的同素异形体，而不是SO2 8-10。本文报道了利用JWST的中红外仪器（MIRI）对WASP-107 b透射光谱中SO2的两个基本振动带（7.35 μm和8.69 μm）的9σ探测。这一发现将WASP-107 b确定为第二颗被证实具有光化学作用的辐照系外行星，将表现出检测到的光化学作用的系外行星的温度范围从1,200 K扩展到740 K。此外，我们的光谱分析揭示了硅酸盐云的存在，这是强烈的青睐（107 σ）比简单的云设置。此外，检测到水（δ 12σ），但未检测到甲烷。这些发现提供了化学不平衡的证据，并表明具有超太阳金属丰度的动态活跃大气。
WASP-107b is a warm (∼ 740K) transiting planet with a Neptune-like mass of∼ 30.5 M⊕ and Jupiter-like radius of∼ 0.94 RJ 1, 2 whose extended atmosphere is eroding 3. Previous observations showed evidence for water vapour and a thick high-altitude condensate layer in WASP-107b’s atmosphere 4, 5. Recently, photochemically produced sulphur dioxide (SO2) was detected in the atmosphere of a hot (∼ 1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 µm 6, 7, but for temperatures below∼ 1,000 K sulphur is predicted to preferably form sulphur allotropes instead of SO2 8–10. Here we report the 9σ-detection of two fundamental vibration bands of SO2, at 7.35 µm and 8.69 µm, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of the JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from∼ 1,200 K down to∼ 740 K. Additionally, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured (∼ 7σ) over simpler cloud setups. Furthermore, water is detected (∼ 12σ), but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity.