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Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab

Nikolov, N. and Sing, D. K. and Goyal, J. and Henry, G. W. and Wakeford, H. R. and Evans, T. M. and López-Morales, M. and García Muñoz, A. and Ben-Jaffel, L. and Sanz-Forcada, J. and Ballester, G. E. and Kataria, T. and Barstow, J. K. and Bourrier, V. and Buchhave, L. A. and Cohen, O. and Deming, D. and Ehrenreich, D. and Knutson, H. and Lavvas, P. and Lecavelier des Etangs, A. and Lewis, N. K. and Mandell, A. M. and Williamson, M. H. (2017) 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. ISSN 0035-8711. doi:10.1093/mnras/stx2865.

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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 T_p = 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Nikolov, N.0000-0002-6500-3574
Sing, D. K.0000-0001-6050-7645
Henry, G. W.0000-0003-4155-8513
Wakeford, H. R.0000-0003-4328-3867
Evans, T. M.0000-0001-5442-1300
López-Morales, M.0000-0003-3204-8183
Kataria, T.0000-0003-3759-9080
Barstow, J. K.0000-0003-3726-5419
Bourrier, V.0000-0002-9148-034X
Buchhave, L. A.0000-0003-1605-5666
Deming, D.0000-0001-5727-4094
Ehrenreich, D.0000-0001-9704-5405
Knutson, H.0000-0002-0822-3095
Lecavelier des Etangs, A.0000-0002-5637-5253
Lewis, N. K.0000-0002-8507-1304
Mandell, A. M.0000-0002-8119-3355
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 October 31. Received 2017 October 11; in original form 2017 August 5. The authors are happy to thank D. Foreman-Mackey, J. Schwartz and V. Parmentier for fruitful discussions and help during the course of this work. This work is based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute (STScI) operated by AURA, Inc. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. NN, DKS and TME acknowledge funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 336792. JG acknowledges support from a Leverhulme Trust Research Project Grant. 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 and from the Space Telescope Science Institue under HST-GO-14767. This work has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). DE and VB acknowledge the financial support of the SNSF. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project FOUR ACES; grant agreement No 724427).
Group:Astronomy Department
Funding AgencyGrant Number
European Research Council (ERC)336792
Leverhulme TrustUNSPECIFIED
Tennessee State UniversityUNSPECIFIED
State of Tennessee Centers of Excellence programUNSPECIFIED
Swiss National Science Foundation (SNSF)UNSPECIFIED
European Research Council (ERC)724427
Space Telescope Science InstituteUNSPECIFIED
Subject Keywords:techniques: spectroscopic, planets and satellites: atmospheres, planets and satellites: individual: HAT-P-32Ab, stars: individual: HAT-P-32A
Issue or Number:2
Record Number:CaltechAUTHORS:20180302-074740821
Persistent URL:
Official Citation:N. Nikolov, D. K. Sing, J. Goyal, G. W. Henry, H. R. Wakeford, T. M. Evans, M. López-Morales, A. García Muñoz, L. Ben-Jaffel, J. Sanz-Forcada, G. E. Ballester, T. Kataria, J. K. Barstow, V. Bourrier, L. A. Buchhave, O. Cohen, D. Deming, D. Ehrenreich, H. Knutson, P Lavvas, A. Lecavelier des Etangs, N. K. Lewis, A. M. Mandell, M. H. Williamson; Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab, Monthly Notices of the Royal Astronomical Society, Volume 474, Issue 2, 21 February 2018, Pages 1705–1717,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85053
Deposited By: Ruth Sustaita
Deposited On:02 Mar 2018 16:24
Last Modified:15 Nov 2021 20:25

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