Nikolov, N;
Sing, DK;
Goyal, J;
Henry, GW;
Wakeford, HR;
Evans, TM;
Lopez-Morales, M;
... Williamson, MH; + view all
(2018)
Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab.
Monthly Notices of the Royal Astronomical Society
, 474
(2)
pp. 1705-1717.
10.1093/mnras/stx2865.
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Abstract
We present a thermal emission spectrum of the bloated hot Jupiter HAT-P-32Ab from a single eclipse observation made in spatial scan mode with the Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope (HST). The spectrum covers the wavelength regime from 1.123 to 1.644 μm which is binned into 14 eclipse depths measured to an averaged precision of 104 parts-per million. The spectrum is unaffected by a dilution from the close M-dwarf companion HAT-P-32B, which was fully resolved. We complemented our spectrum with literature results and performed a comparative forward and retrieval analysis with the 1D radiative-convective ATMO model. Assuming solar abundance of the planet atmosphere, we find that the measured spectrum can best be explained by the spectrum of a blackbody isothermal atmosphere with Tp = 1995 ± 17 K, but can equally well be described by a spectrum with modest thermal inversion. The retrieved spectrum suggests emission from VO at the WFC3 wavelengths and no evidence of the 1.4 μm water feature. The emission models with temperature profiles decreasing with height are rejected at a high confidence. An isothermal or inverted spectrum can imply a clear atmosphere with an absorber, a dusty cloud deck or a combination of both. We find that the planet can have continuum of values for the albedo and recirculation, ranging from high albedo and poor recirculation to low albedo and efficient recirculation. Optical spectroscopy of the planet's day-side or thermal emission phase curves can potentially resolve the current albedo with recirculation degeneracy.
| Type: | Article |
|---|---|
| Title: | Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stx2865 |
| Publisher version: | http://doi.org/10.1093/mnras/stx2865 |
| Language: | English |
| Additional information: | © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, techniques: spectroscopic, planets and satellites: atmospheres, planets and satellites: individual: HAT-P-32Ab, stars: individual: HAT-P-32A, SYSTEMATIC RETRIEVAL ANALYSIS, EXOPLANET HD 189733B, TRANSMISSION SPECTRUM, HOT JUPITERS, SPACE-TELESCOPE, TEMPERATURE INVERSION, MODEL ATMOSPHERES, DWARF ATMOSPHERES, EMISSION-SPECTRUM, THERMAL INVERSION |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10045156 |
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