Astrophys. J., 827, 19-19 (2016/August-2)
HST hot-Jupiter transmission spectral survey: clear skies for cool Saturn WASP-39b.
FISCHER P.D., KNUTSON H.A., SING D.K., HENRY G.W., WILLIAMSON M.W., FORTNEY J.J., BURROWS A.S., KATARIA T., NIKOLOV N., SHOWMAN A.P., BALLESTER G.E., DESERT J.-M., AIGRAIN S., DEMING D., LECAVELIER DES ETANGS A. and VIDAL-MADJAR A.
Abstract (from CDS):
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.
© 2016. The American Astronomical Society. All rights reserved.
planetary systems - planets and satellites: atmospheres - stars: individual: WASP-39 - techniques: spectroscopic - techniques: spectroscopic
View the reference in ADS
To bookmark this query, right click on this link: simbad:2016ApJ...827...19F and select 'bookmark this link' or equivalent in the popup menu