论文标题
与JWST NIRSPEC G395H的系外行星WASP-39B的早期发行科学
Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
论文作者
论文摘要
测量系外星大气中碳和氧的丰度被认为是解锁外部系统的形成和演变的关键途径。访问系外行星的化学清单需要高精度观察结果，这通常是根据具有低分辨率空间基于空间和高分辨率地面设施的个体分子检测来推断的。在这里，我们报告了在3-5 $μ$ M之间的中分辨率（r $ \ sim $ 600）的传输光谱，涵盖了用JWST NIRSPEC G395H获得的土星质量系质WASP-39B的多重吸收特征。我们的观察结果达到了1.46倍的光子精度，每个光谱箱的平均过境深度不确定性为221 ppm，并且对系统效应的影响最小。我们从Co $ _2 $（28.5 $σ$）和H $ _2 $ O（21.5 $σ$）中检测到大量吸收，并识别SO $ _2 $作为4.1 $ $ m（4.8 $σ$）的吸收来源。最佳拟合大气模型范围在3至10倍太阳金属范围之间，具有次极到太阳C/O比。这些结果，包括检测到So $ _2 $，强调了在系外行星大气中表征化学反应的重要性，并将NIRSPEC G395H展示为在此关键波长范围内时间序列观测的绝佳模式。
Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems. Access to an exoplanet's chemical inventory requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based and high-resolution ground-based facilities. Here we report the medium-resolution (R$\sim$600) transmission spectrum of an exoplanet atmosphere between 3-5 $μ$m covering multiple absorption features for the Saturn-mass exoplanet WASP-39b, obtained with JWST NIRSpec G395H. Our observations achieve 1.46x photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO$_2$ (28.5$σ$) and H$_2$O (21.5$σ$), and identify SO$_2$ as the source of absorption at 4.1 $μ$m (4.8$σ$). Best-fit atmospheric models range between 3 and 10x solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO$_2$, underscore the importance of characterising the chemistry in exoplanet atmospheres, and showcase NIRSpec G395H as an excellent mode for time series observations over this critical wavelength range.
