Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab
Sing, D. K.
Henry, G. W.
Wakeford, H. R.
Evans, T. M.
García Muñoz, A.
Ballester, G. E.
Barstow, J. K.
Buchhave, L. A.
Lecavelier des Etangs, A.
Lewis, N. K.
Mandell, A. M.
Williamson, M. H.
AffiliationUniv Arizona, Lunar & Planetary Lab
planets and satellites: atmospheres
planets and satellites: individual: HAT-P-32Ab
stars: individual: HAT-P-32A
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationHubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab 2018, 474 (2):1705 Monthly Notices of the Royal Astronomical Society
Rights© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractWe 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 mu m 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 mu m 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.
VersionFinal published version
SponsorsEuropean Research Council under the European Unions Seventh Framework Programme (FP7)/ERC ; Leverhulme Trust Research Project Grant; Space Telescope Science Institue [HST-GO-14767]; Swiss National Science Foundation (SNSF); SNSF; European Research Council (ERC) under the European Union's Horizon research and innovation programme (project FOUR ACES)