Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b
Abstract
We present the transmission spectrum of HAT-P-12b through a joint analysis of data obtained from the Hubble Space Telescope Space Telescope Imaging Spectrograph and Wide Field Camera 3 and Spitzer, covering the wavelength range 0.3–5.0 μm. We detect a muted water vapor absorption feature at 1.4 μm attenuated by clouds, as well as a Rayleigh scattering slope in the optical indicative of small particles. We interpret the transmission spectrum using both the state-of-the-art atmospheric retrieval code SCARLET and the aerosol microphysics model CARMA. These models indicate that the atmosphere of HAT-P-12b is consistent with a broad range of metallicities between several tens to a few hundred times solar, a roughly solar C/O ratio, and moderately efficient vertical mixing. Cloud models that include condensate clouds do not readily generate the submicron particles necessary to reproduce the observed Rayleigh scattering slope, while models that incorporate photochemical hazes composed of soot or tholins are able to match the full transmission spectrum. From a complementary analysis of secondary eclipses by Spitzer, we obtain measured depths of 0.042% ± 0.013% and 0.045% ± 0.018% at 3.6 and 4.5 μm, respectively, which are consistent with a blackbody temperature of 890⁺⁶⁰₋₇₀ K and indicate efficient day–night heat recirculation. HAT-P-12b joins the growing number of well-characterized warm planets that underscore the importance of clouds and hazes in our understanding of exoplanet atmospheres.
Additional Information
© 2020 The American Astronomical Society. Received 2019 May 17; revised 2020 February 7; accepted 2020 April 7; published 2020 April 23. 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 also 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. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013)/ERC grant agreement No. 336792. Support for this work was also provided by NASA/STScI through grants linked to the HST-GO-12473 and HST-GO-14767 programs. I.W. and P.G. are supported by Heising-Simons Foundation 51 Pegasi b postdoctoral fellowships. H.A.K. acknowledges support from the Sloan Foundation.Attached Files
Published - Wong_2020_AJ_159_234.pdf
Submitted - 2004.03551.pdf
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Additional details
- Eprint ID
- 102647
- Resolver ID
- CaltechAUTHORS:20200420-101335006
- NASA/JPL/Caltech
- 336792
- European Research Council (ERC)
- HST-GO-12473
- NASA
- HST-GO-14767
- NASA
- 51 Pegasi b Fellowship
- Heising-Simons Foundation
- Alfred P. Sloan Foundation
- Created
-
2020-04-20Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, Division of Geological and Planetary Sciences