发表机构
University of Virginia; University of Michigan; University of St Andrews; Space Telescope Science Institute; Johns Hopkins University; European Southern Observatory（弗吉尼亚大学; 密歇根大学; 圣安德鲁斯大学; 太空望远镜科学研究所; 约翰斯·霍普金斯大学; 欧洲南方天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用JWST NIRSpec G395H首次在热土星WASP-52b大气中探测到CO2和H2O，并发现高层云与恒星黑子证据，表明活跃恒星行星仍可进行透射光谱表征。
AI 中文摘要
围绕活跃恒星运行的外行星为利用JWST进行大气表征带来了独特的挑战。在这类世界中，热土星WASP-52b（平衡温度约1300 K）绕一颗活跃的K型矮星运行，恒星污染使透射光谱分析变得复杂。在此，我们展示了通过JWST晨昏计划（GO-3969）获得的WASP-52b首个JWST NIRSpec G395H（2.8-5.2微米）临边平均透射光谱，该计划旨在测量热巨行星样本的临边不对称性。我们的光谱首次在WASP-52b大气中探测到CO2（ln B = 54 / >10σ），其反演丰度为log CO2 = -5.09（+1.09/-1.14），并确认了H2O（ln B = 5.9 / 约3-4σ），丰度为log H2O = -3.41（+1.04/-1.04）。我们发现一个陡峭的近红外斜率，无法仅由H2O吸收解释，这需要未被掩蔽的恒星黑子（ln B = 5.7 / 约3-4σ），尽管其性质在我们的数据缩减中有所变化。分子带的形状和振幅还表明存在高层（<10毫巴）非均匀云层，覆盖了约40 ± 20%的晨昏圈（ln B = 1.9 / 约2.5σ），这为晨昏临边差异提供了证据，而这是大气环流模型的共识预测。由于成分、云层和恒星黑子之间的简并导致分子丰度存在数量级的不确定性，WASP-52b的大气金属丰度可能为亚太阳、太阳或超太阳。然而，化学平衡反演提供了相似的统计拟合，同时倾向于更严格的约束，即超太阳金属丰度（M/H = 14.8（+12.1/-5.9）倍太阳）。这些结果强调，对于围绕活跃恒星运行的行星，通过透射光谱仍可恢复化学探测和气溶胶特性。
英文摘要
Exoplanets orbiting active stars offer distinct challenges for atmospheric characterization with the JWST. Among such worlds, the hot Saturn WASP-52b (Teq $\sim$ 1300 K) orbits an active K-dwarf that complicates transmission spectroscopy via stellar contamination. Here, we present the first JWST NIRSpec G395H (2.8-5.2 $μ$m) limb-averaged transmission spectrum of WASP-52b obtained through the JWST Morning/Evening Program (GO-3969), which aims to measure limb asymmetries across a sample of hot giant exoplanets. Our spectrum reveals the first detection of CO2 in WASP-52b's atmosphere (ln B = 54 / >10$σ$), with a retrieved abundance of log CO2 = -5.09 (+1.09/-1.14), and confirmation of H2O (ln B = 5.9 / $\sim$3-4$σ$), with an abundance of log H2O = -3.41 (+1.04/-1.04). We find a steep near-infrared slope that cannot be explained solely by H2O absorption, necessitating unocculted starspots (ln B = 5.7 / $\sim$3-4$σ$), though with properties that vary across our data reductions. The shape and amplitude of the molecular bands additionally suggest high-altitude (<10 mbar) inhomogeneous clouds covering $\approx$40 $\pm$ 20% of the terminator (ln B = 1.9 / $\sim$2.5$σ$), which provides evidence for the morning-evening terminator differences that are consensus predictions of general circulation models. WASP-52b's atmospheric metallicity can be sub-solar, solar, or super-solar, due to order-of-magnitude uncertainties in the molecular abundances caused by degeneracies between compositions, clouds, and starspots. However, chemical equilibrium retrievals provide a similar statistical fit while favoring a tighter constraint with a super-solar metallicity (M/H = 14.8 (+12.1/-5.9) $\times$ solar). These results highlight that chemical detections and aerosol properties may still be recovered for planets orbiting active stars via transmission spectroscopy.
Comments18 pages, 8 figures
