摘要：We present observations of WASP-63b by the Hubble Space Telescope (HST) as part of “A Preparatory Programto Identify the Single Best Transiting Exoplanet for James Webb Space Telescope (JWST) Early Release Science(ERS).” WASP-63b is one of the community targets under consideration for the JWST ERS program. We present aspectrum derived from a single observation by HST Wide Field Camera3 in the near-infrared. We engaged groupsacross the transiting exoplanet community to participate in the analysis of the data and present results from each.Extraction of the transmission spectrum by several independent analyses find an H 2 O absorption feature withvarying degrees of significance ranging from 1σ to 3σ. The feature, in all cases, is muted in comparison to a clearatmosphere at solar composition. The reasons for the muting of this feature are ambiguous due to a degeneracybetween clouds and composition. The data does not yield robust detections of any molecular species other thanH 2 O. The group was motivated to perform an additional set of retrieval exercises to investigate an apparent bumpin the spectrum at ∼1.55 μm. We explore possible disequilibrium chemistry and find this feature is consistent withsuper-solar HCN abundance but it is questionable if the required mixing ratio of HCN is chemically and physicallyplausible. The ultimate goal of this study is to vet WASP-63b as a potential community target to best demonstratethe capabilities and systematics of JWST instruments for transiting exoplanet science. In the case of WASP-63b,the presence of a detectable water feature indicates that WASP-63b remains a plausible target for JWSTobservations.
关键词：atmospheric effects;planets and satellites: atmospheres;planets and satellites: individual (WASP- 63b);techniques: spectroscopic
