LRG-BEASTS: Sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2
LRG-BEASTS: Sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2
复制标题
LRG-BEASTS：使用 NTT/EFOSC2 在 WASP-94A b 大气中进行钠吸收和瑞利散射
DOI：
10.1093/mnras/stab3805
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发表时间：
2022
影响因子：
4.8
通讯作者：
Ahrer E
中科院分区：
文献类型：
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作者：
Ahrer E
我们展示了 WASP-94A b 的光学透射光谱，这是这颗高度膨胀的热木星的第一个大气特征。据报道，这颗行星的半径为 RJup，质量仅为 MJup，平衡温度为 1508 ± 75 K。我们使用位于智利拉西拉的 ESO 新技术望远镜 (NTT) 上的 EFOSC2 仪器对这颗行星进行了光谱观测：NTT/EFOSC2 首次用于透射光谱。对于 ∼200 Å 的 bin 宽度，我们实现了 128 ppm 的平均传输深度精度。这种高精度部分是通过链接所有波长段的高斯过程超参数来实现的。由此产生的透射光谱跨越 3800–7140 Å 的波长范围，显示出显着性为 4.9σ 的钠吸收，表明大气相对无云。钠信号可能会变宽，最佳拟合宽度为 Å，而仪器分辨率为 27.2 ± 0.2 Å。我们还在透射光谱的蓝色端检测到陡峭的斜率，表明 WASP-94A b 大气中存在瑞利散射。检索模型显示了观察到的斜率是超瑞利的证据，并讨论了潜在的原因。最后，我们在 WASP-94A 的 CaII H&K 线中发现了狭窄的吸收核心，表明这颗恒星被逃离热木星的气体所笼罩。
We present an optical transmission spectrum for WASP-94A b, the first atmospheric characterization of this highly-inflated hot Jupiter. The planet has a reported radius ofRJup, a mass of onlyMJup, and an equilibrium temperature of 1508 ± 75 K. We observed the planet transit spectroscopically with the EFOSC2 instrument on the ESO New Technology Telescope (NTT) at La Silla, Chile: the first use of NTT/EFOSC2 for transmission spectroscopy. We achieved an average transit-depth precision of 128 ppm for bin widths of ∼200 Å. This high precision was achieved in part by linking Gaussian Process hyperparameters across all wavelength bins. The resulting transmission spectrum, spanning a wavelength range of 3800–7140 Å, exhibits a sodium absorption with a significance of 4.9σ, suggesting a relatively cloud-free atmosphere. The sodium signal may be broadened, with a best-fitting width ofÅ in contrast to the instrumental resolution of 27.2 ± 0.2 Å. We also detect a steep slope in the blue end of the transmission spectrum, indicating the presence of Rayleigh scattering in the atmosphere of WASP-94A b. Retrieval models show evidence for the observed slope to be super-Rayleigh and potential causes are discussed. Finally, we find narrow absorption cores in the CaII H&K lines of WASP-94A, suggesting the star is enshrouded in gas escaping the hot Jupiter.