Interactions between exoplanetary atmospheres and internal properties have long been hypothesized to be drivers of the inflation mechanisms of gaseous planets and apparent atmospheric chemical disequilibrium conditions¹. However, transmission spectra of exoplanets has been limited in its ability to observational confirm these theories due to the limited wavelength coverage of HST and inferences of single molecules, mostly H₂O (ref. ²). In this work, we present the panchromatic transmission spectrum of the approximately 750 K, low-density, Neptune-sized exoplanet WASP-107b using a combination of HST WFC3, JWST NIRCam and MIRI. From this spectrum, we detect spectroscopic features due to H₂O (21σ), CH₄ (5σ), CO (7σ), CO₂ (29σ), SO₂ (9σ), and NH₃ (6σ). The presence of these molecules enable constraints on the atmospheric metal enrichment (M/H is 10–18× Solar³), vertical mixing strength (log₁₀K_zz = 8.4–9.0 cm²s⁻¹), and internal temperature (>345 K). The high internal temperature is suggestive of tidally-driven inflation⁴ acting upon a Neptunelike internal structure, which can naturally explain the planet’s large radius and low density. These findings suggest that eccentricity driven tidal heating is a critical process governing atmospheric chemistry and interior structure inferences for a majority of the cool (<1,000K) super-Earth-to-Saturn mass exoplanet population.

长期以来，外行星大气和内部特性之间的相互作用一直被认为是气态行星膨胀机制和明显大气化学不平衡条件的驱动因素 ¹ 。然而，由于 HST 的波长覆盖范围和单分子（主要是 H ₂ O）的推断有限，系外行星的透射光谱在观测证实这些理论的能力方面受到限制（参考文献 ² O (21σ)、CH ₄ (5σ)、CO (7σ)、CO ₂ (29σ) 的光谱特征)、SO ₂ (9σ) 和 NH ₃ (6σ)。这些分子的存在可以限制大气金属富集（M/H 为 10–18× 太阳 ³ ）、垂直混合强度（log ₁₀ K _zz = 8.4–9.0 cm ² s ⁻¹ )，以及内部温度 (>345 K)。高内部温度表明潮汐驱动的膨胀 ⁴ 作用于类似海王星的内部结构，这可以自然地解释这颗行星的大半径和低密度。这些发现表明，偏心率驱动的潮汐加热是控制大多数冷（<1,000K）超级地对土星质量系外行星群体的大气化学和内部结构推论的关键过程。