HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering

By D. Sing, H. Wakeford, A. Showman, N. Nikolov, Jon Fortney, Adam Burrows, Gilda E. Ballester, D. Deming, Suzanne Aigrain, J. D'esert and 8 more. 2014

150 citations recorded by the source corpus.

We present Hubble Space Telescope optical and near-IR transmission spectra of the transiting hot-Jupiter WASP-31b. The spectrum covers 0.3–1.7 μm at a resolution R ∼ 70, which we combine with Spitzer photometry to cover the full-optical to IR. The spectrum is dominated by a cloud deck with a flat transmission spectrum which is apparent at wavelengths > 0.52 μm. The cloud deck is present at high altitudes and low pressures, as it covers the majority of the expected optical Na line and near-IR H2O features. While Na i absorption is not clearly identified, the resulting spectrum does show a very strong potassium feature detected at the 4.2σ confidence level. Broadened alkali wings are not detected, indicating pressures below ∼10 mbar. The lack of Na and strong K is the first indication of a sub-solar Na/K abundance ratio in a planetary atmosphere (ln[Na/K] = −3.3 ± 2.8), which could potentially be explained by Na condensation on the planet's night side, or primordial abundance variations. A strong Rayleigh scattering signature is detected at short wavelengths, with a 4σ significant slope. Two distinct aerosol size populations can explain the spectra, with a smaller sub-micron size grain population reaching high altitudes producing a blue Rayleigh scattering signature on top of a larger, lower lying population responsible for the flat cloud deck at longer wavelengths. We estimate that the atmospheric circulation is sufficiently strong to mix micron size particles upwards to the required 1–10 mbar pressures, necessary to explain the cloud deck. These results further confirm the importance of clouds in hot Jupiters, which can potentially dominate the overall spectra and may alter the abundances of key gaseous species.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/68acea61938e29b9cef7aa66ebdc75a6e2ea8985

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. D. Sing
3. Jon Fortney
4. D. Deming
5. A. Showman
6. Suzanne Aigrain
7. H. Wakeford
8. H. Knutson

Citations in the corpus

• A Population Study of Gaseous Exoplanets (2017, unknown): “…b (Damiano et al. 2017), HD 209458 b (Deming et al. 2013), HD 189733 b (McCullough et al. 2014), WASP12 b (Kreidberg et al. 2015), WASP-31 b (Sing et al. 2015), WASP-43 b (Kreidberg et al. 2014a), WASP-101 b (Wakeford et al. 2017), WASP-121 b (Evans et al. 2016) and XO-1 b (Deming et al.…”
• The Complete Transmission Spectrum of WASP-39b with a Precise Water Constraint (2017, background): “…(Na and K) and molecular (H2O) absorption in a range of exoplanet atmospheres with ground- and space-based telescopes (e.g. Charbonneau et al. 2002; Sing et al. 2011, 2015; Deming et al. 2013; Kreidberg et al. 2014; Stevenson et al. 2014; Nikolov et al. 2016; Sing et al. 2016; Evans et al. 2016).”
• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, unknown): “P-96b (193), WASP-127b (53), HAT-P-1b (195), XO-2b (245) Continued on next page 18 N. Madhusudhan Table 1 { Continued from previous page Chemical Species Planet (References) K WASP-6b (192), WASP-31b (247), WASP-39b (244), WASP-127b (53), HAT-P-12b (244), XO-2b (243), HD 80606b (55) TiO WASP-19b (23”
• Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph (2015, background): “…these encouraging works, the presence of scattering hazes and clouds (Lecavelier Des Etangs et al. 2008a,b; Pont et al. 2013) in several exoplanets prevented the detection of major chemical constituents at low to medium resolution even from space (e.g., Kreidberg et al. 2014; Sing et al. 2015).”
• HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b (2017, background): “However, a significant number also show little or no evidence of water absorption (e.g., Line et al. 2013; Ehrenreich et al. 2014; Knutson et al. 2014; Sing et al. 2015), which is plausibly due to clouds high in the planetary atmosphere (Sing et al. 2016).”
• A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, background): “…in Sing et al. (2016) (for additional details of observations, see Pont et al. 2013; Line et al. 2013a; Huitson et al. 2013; Mandell et al. 2013; Sing et al. 2013, 2015; Wakeford et al. 2013; Nikolov et al. 2014, 2015; McCullough et al. 2014) represent a variety of atmospheres, interpreted as a…”
• DETECTION OF H2O AND EVIDENCE FOR TiO/VO IN AN ULTRA-HOT EXOPLANET ATMOSPHERE (2016, background): “Transmission spectra at optical wavelengths show evidence for Rayleigh scattering by molecular hydrogen and high-altitude aerosols, and absorption by alkali metals (e.g. Charbonneau et al. 2002; Pont et al. 2008; Sing et al. 2013, 2015; Nikolov et al. 2014, 2015).”