A comprehensive analysis of WASP-17b's transmission spectrum from space-based observations
A comprehensive analysis of WASP-17b's transmission spectrum from space-based observations
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DOI：
10.1093/mnras/stac661
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发表时间：
2022-04-06
影响因子：
4.8
通讯作者：
Kataria, T.
中科院分区：
文献类型：
--
作者：
Alderson, L.;Wakeford, H. R.;Kataria, T.
由于其1770 K的平衡温度，WASP-17 b是一颗1.99 R-Jup，0.486 M-Jup的系外行星，位于高温和超高温彗星之间的关键时刻。我们提出了它的0.3-5 μ m的透射光谱，新获得的哈勃空间望远镜（HST）宽视场相机3（WFC 3）的测量，并利用改进的分析技术，重新分析HST空间望远镜成像光谱仪和斯皮策空间望远镜红外阵列相机的观测。我们实现了132 ppm的中位精度，整个光谱的平均值为272 ppm。我们还利用凌日系外行星勘测卫星（TESS）和地面凌日观测来改进WASP-17 b的轨道周期。为了解释观测到的大气，我们利用自由和平衡化学检索使用的POSEIDON和ATMO检索代码，分别。我们在>7 sigma处检测到由于H2O的吸收，并在>3 sigma处发现由于CO2的吸收的证据。我们没有看到以前检测到的Na I和K I吸收的证据。在一个广泛的检索配置套件，我们发现，数据有利于高或低金属度模式的双峰解决方案，由于在光学约束差，并证明了使用多个统计模型选择的重要性。未来的JWST GTO观测，结合目前的透射光谱，将能够精确限制WASP-17 b的大气层。
Due to its 1770 K equilibrium temperature, WASP-17b, a 1.99 R-Jup, 0.486 M-Jup exoplanet, sits at the critical juncture between hot and ultra-hot Jupiters. We present its 0.3-5 mu m transmission spectrum, newly obtained with Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) measurements, and, taking advantage of improved analysis techniques, reanalysed HST Space Telescope Imaging Spectrograph and Spitzer Space Telescope Infrared Array Camera observations. We achieve a median precision of 132 ppm, with a mean of 272 ppm across the whole spectrum. We additionally make use of Transiting Exoplanet Survey Satellite (TESS) and ground-based transit observations to refine the orbital period of WASP-17b. To interpret the observed atmosphere, we make use of free and equilibrium chemistry retrievals using the POSEIDON and ATMO retrieval codes, respectively. We detect absorption due to H2O at >7 sigma and find evidence of absorption due to CO2 at >3 sigma. We see no evidence of previously detected Na I and K I absorption. Across an extensive suite of retrieval configurations, we find that the data favour a bimodal solution with high- or low-metallicity modes as a result of poor constraints in the optical and demonstrate the importance of using multiple statistics for model selection. Future JWST GTO observations, combined with the presented transmission spectrum, will enable precise constraints on WASP-17b's atmosphere.