dc.contributor.author | Fischer, PD | |
dc.contributor.author | Knutson, HA | |
dc.contributor.author | Sing, DK | |
dc.contributor.author | Henry, GW | |
dc.contributor.author | Williamson, MW | |
dc.contributor.author | Fortney, JJ | |
dc.contributor.author | Burrows, AS | |
dc.contributor.author | Kataria, T | |
dc.contributor.author | Nikolov, N | |
dc.contributor.author | Showman, AP | |
dc.contributor.author | Ballester, GE | |
dc.contributor.author | Désert, J-M | |
dc.contributor.author | Aigrain, S | |
dc.contributor.author | Deming, D | |
dc.contributor.author | Lecavelier des Etangs, A | |
dc.contributor.author | Vidal-Madjar, A | |
dc.date.accessioned | 2016-08-12T13:34:09Z | |
dc.date.issued | 2016-08-03 | |
dc.description.abstract | We present the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) optical transmission spectroscopy of the cool Saturn-mass exoplanet WASP-39b from 0.29-1.025 μm, along with complementary transit observations from Spitzer IRAC at 3.6 and 4.5 μm. The low density and large atmospheric pressure scale height of WASP-39b make it particularly amenable to atmospheric characterization using this technique. We detect a Rayleigh scattering slope as well as sodium and potassium absorption features; this is the first exoplanet in which both alkali features are clearly detected with the extended wings predicted by cloud-free atmosphere models. The full transmission spectrum is well matched by a clear H2-dominated atmosphere, or one containing a weak contribution from haze, in good agreement with the preliminary reduction of these data presented in Sing et al. WASP-39b is predicted to have a pressure-temperature profile comparable to that of HD 189733b and WASP-6b, making it one of the coolest transiting gas giants observed in our HST STIS survey. Despite this similarity, WASP-39b appears to be largely cloud-free, while the transmission spectra of HD 189733b and WASP-6b both indicate the presence of high altitude clouds or hazes. These observations further emphasize the surprising diversity of cloudy and cloud-free gas giant planets in short-period orbits and the corresponding challenges associated with developing predictive cloud models for these atmospheres. | en_GB |
dc.description.sponsorship | The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013)/ERC grant agreement no. 336792. Support for this work was provided by NASA through grants under the HST-GO-12473 program from the STScI. G.W.H. and M.H.W. acknowledge long-term support from Tennessee State University and the State of Tennessee through its Centers of Excellence program. | en_GB |
dc.identifier.citation | Vol. 827 (1), article 19 | en_GB |
dc.identifier.doi | 10.3847/0004-637X/827/1/19 | |
dc.identifier.uri | http://hdl.handle.net/10871/22990 | |
dc.language.iso | en | en_GB |
dc.publisher | American Astronomical Society | en_GB |
dc.title | HST hot-Jupiter transmission spectral survey: clear skies for cool Saturn WASP-39b | en_GB |
dc.type | Article | en_GB |
dc.date.available | 2016-08-12T13:34:09Z | |
dc.identifier.issn | 1538-4357 | |
dc.description | This is the final version of the article. Available from American Astronomical Society/IOP Publishing via the DOI in this record. | en_GB |
dc.identifier.journal | Astrophysical Journal | en_GB |