HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
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 $\mu$m at a resolution $R\sim$70, which we combine with Spitzer photometry to cover the full-optical to IR. The spectrum is dominated by a cloud-deck with a...
| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Journal article |
| Published: |
2014
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| _version_ | 1826298344096399360 |
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| author | Sing, D Wakeford, H Showman, A Nikolov, N Fortney, J Burrows, A Ballester, G Deming, D Aigrain, S Désert, J Gibson, N Henry, G Knutson, H Etangs, A Pont, F Vidal-Madjar, A Williamson, M Wilson, P |
| author_facet | Sing, D Wakeford, H Showman, A Nikolov, N Fortney, J Burrows, A Ballester, G Deming, D Aigrain, S Désert, J Gibson, N Henry, G Knutson, H Etangs, A Pont, F Vidal-Madjar, A Williamson, M Wilson, P |
| author_sort | Sing, D |
| collection | OXFORD |
| description | 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 $\mu$m at a resolution $R\sim$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 $>0.52\mu$m. 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 H$_2$O features. While Na I absorption is not clearly identified, the resulting spectrum does show a very strong potassium feature detected at the 4.2-$\sigma$ confidence level. Broadened alkali wings are not detected, indicating pressures below $\sim$10 mbar. The lack of Na and strong K is the first indication of a sub-solar Na/K abundance ratio in a planetary atmosphere (ln[Na/K]$=-3.3\pm2.8$), which could potentially be explained by Na condensation on the planet's night side, or primordial abundance variations. A strong Rayleigh scattering signature is detected at short wavelengths, with a 4-$\sigma$ 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 upward 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. |
| first_indexed | 2024-03-07T04:45:22Z |
| format | Journal article |
| id | oxford-uuid:d30ec2fc-88dd-459c-af42-bc5c49e00ddd |
| institution | University of Oxford |
| last_indexed | 2024-03-07T04:45:22Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:d30ec2fc-88dd-459c-af42-bc5c49e00ddd2022-03-27T08:08:46ZHST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scatteringJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:d30ec2fc-88dd-459c-af42-bc5c49e00dddSymplectic Elements at Oxford2014Sing, DWakeford, HShowman, ANikolov, NFortney, JBurrows, ABallester, GDeming, DAigrain, SDésert, JGibson, NHenry, GKnutson, HEtangs, APont, FVidal-Madjar, AWilliamson, MWilson, PWe present Hubble Space Telescope optical and near-IR transmission spectra of the transiting hot-Jupiter WASP-31b. The spectrum covers 0.3-1.7 $\mu$m at a resolution $R\sim$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 $>0.52\mu$m. 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 H$_2$O features. While Na I absorption is not clearly identified, the resulting spectrum does show a very strong potassium feature detected at the 4.2-$\sigma$ confidence level. Broadened alkali wings are not detected, indicating pressures below $\sim$10 mbar. The lack of Na and strong K is the first indication of a sub-solar Na/K abundance ratio in a planetary atmosphere (ln[Na/K]$=-3.3\pm2.8$), which could potentially be explained by Na condensation on the planet's night side, or primordial abundance variations. A strong Rayleigh scattering signature is detected at short wavelengths, with a 4-$\sigma$ 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 upward 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. |
| spellingShingle | Sing, D Wakeford, H Showman, A Nikolov, N Fortney, J Burrows, A Ballester, G Deming, D Aigrain, S Désert, J Gibson, N Henry, G Knutson, H Etangs, A Pont, F Vidal-Madjar, A Williamson, M Wilson, P HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering |
| title | HST hot-Jupiter transmission spectral survey: detection of potassium in
WASP-31b along with a cloud deck and Rayleigh scattering |
| title_full | HST hot-Jupiter transmission spectral survey: detection of potassium in
WASP-31b along with a cloud deck and Rayleigh scattering |
| title_fullStr | HST hot-Jupiter transmission spectral survey: detection of potassium in
WASP-31b along with a cloud deck and Rayleigh scattering |
| title_full_unstemmed | HST hot-Jupiter transmission spectral survey: detection of potassium in
WASP-31b along with a cloud deck and Rayleigh scattering |
| title_short | HST hot-Jupiter transmission spectral survey: detection of potassium in
WASP-31b along with a cloud deck and Rayleigh scattering |
| title_sort | hst hot jupiter transmission spectral survey detection of potassium in wasp 31b along with a cloud deck and rayleigh scattering |
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