WASP-39b is a hot Saturn-mass exoplanet with a predicted clear atmosphere based on observations in the optical and infrared. Here, we complete the transmission spectrum of the atmosphere with observations in the near-infrared (NIR) over three water absorption features with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) G102 (0.8-1.1 mu m) and G141 (1.1-1.7 mu m) spectroscopic grisms. We measure the predicted high-amplitude H2O feature centered at 1.4 mu m and the smaller amplitude features at 0.95 and 1.2 mu m, with a maximum water absorption amplitude of 2.4 planetary scale heights. We incorporate these new NIR measurements into previously published observational measurements to complete the transmission spectrum from 0.3 to 5 mu m. From these observed water features, combined with features in the optical and IR, we retrieve a well constrained temperature T-eq = 1030(20)(+30) K, and atmospheric metallicity 151(46) (+48) solar, which is relatively high with respect to the currently established mass-metallicity trends. This new measurement in the Saturn-mass range hints at further diversity in the planet formation process relative to our solar system giants.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626406 |
| Date | 20 December 2017 |
| Creators | Wakeford, H. R., Sing, D. K., Deming, D., Lewis, N. K., Goyal, J., Wilson, T. J., Barstow, J., Kataria, T., Drummond, B., Evans, T. M., Carter, A. L., Nikolov, N., Knutson, H. A., Ballester, G. E., Mandell, A. M. |
| Contributors | Univ Arizona, Lunar & Planetary Lab |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/1538-3881/155/i=1/a=29?key=crossref.514ec2fba37ccb9b9b304f11dc745af0 |
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