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Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3

Beatty, Thomas G. and Madhusudhan, Nikku and Tsiaras, Angelos and Zhao, Ming and Gilliland, Ronald L. and Knutson, Heather A. and Shporer, Avi and Wright, Jason T. (2017) Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3. Astronomical Journal, 154 (4). Art. No. 158. ISSN 1538-3881. doi:10.3847/1538-3881/aa899b.

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We observed two eclipses of the Kepler-13A planetary system, on UT 2014 April 28 and UT 2014 October 13, in the near-infrared using Wide Field Camera 3 on the Hubble Space Telescope. By using the nearby binary stars Kepler-13BC as a reference, we were able to create a differential light curve for Kepler-13A that had little of the systematics typically present in HST/WFC3 spectrophotometry. We measure a broadband (1.1–1.65 μm) eclipse depth of 734 ± 28 ppm and are able to measure the emission spectrum of the planet at R ≈ 50 with an average precision of 70 ppm. We find that Kepler-13Ab possesses a noninverted, monotonically decreasing vertical temperature profile. We exclude an isothermal profile and an inverted profile at more than 3σ. We also find that the dayside emission of Kepler-13Ab appears generally similar to an isolated M7 brown dwarf at a similar effective temperature. Due to the relatively high mass and surface gravity of Kepler-13Ab, we suggest that the apparent lack of an inversion is due to cold-trap processes in the planet's atmosphere. Using a toy model for where cold traps should inhibit inversions, as well as observations of other planets in this temperature range with measured emission spectra, we argue that with more detailed modeling and more observations we may be able to place useful constraints on the size of condensates on the daysides of hot Jupiters.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Beatty, Thomas G.0000-0002-9539-4203
Madhusudhan, Nikku0000-0002-4869-000X
Zhao, Ming0000-0002-4258-9517
Gilliland, Ronald L.0000-0002-1554-5578
Knutson, Heather A.0000-0002-0822-3095
Shporer, Avi0000-0002-1836-3120
Wright, Jason T.0000-0001-6160-5888
Additional Information:© 2017 American Astronomical Society. Received 2016 November 3. Accepted 2017 August 29. Published 2017 September 22. We would like to thank the anonymous referee for their detailed response, which improved the quality of the paper. These observations were made as a part of GO Program 13308 with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under the contract NAS 5-26555. T.G.B., M.Z., and J.T.W. were partially supported by funding from the Center for Exoplanets and Habitable Worlds. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. A.T. was supported by the ERC project ExoLights (617119). M.Z. and J.T.W. acknowledge NASA Origins of Solar Systems grant NNX14AD22G. This work has made use of NASA's Astrophysics Data System, the Exoplanet Orbit Database, and the Exoplanet Data Explorer at (Han et al. 2014); the Extrasolar Planet Encyclopedia at (Schneider et al. 2011); the SIMBAD database operated at CDS, Strasbourg, France (Wenger et al. 2000); and the VizieR catalog access tool, CDS, Strasbourg, France (Ochsenbein et al. 2000).
Group:Astronomy Department
Funding AgencyGrant Number
NASANAS 5-26555
Center for Exoplanets and Habitable WorldsUNSPECIFIED
Pennsylvania State UniversityUNSPECIFIED
Eberly College of ScienceUNSPECIFIED
Pennsylvania Space Grant ConsortiumUNSPECIFIED
European Research Council (ERC)617119
Subject Keywords:planetary systems; planets and satellites: atmospheres; stars: individual (Kepler-13) ; techniques: spectroscopic
Issue or Number:4
Record Number:CaltechAUTHORS:20170922-100939497
Persistent URL:
Official Citation:Thomas G. Beatty et al 2017 AJ 154 158
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81741
Deposited By: Ruth Sustaita
Deposited On:22 Sep 2017 17:40
Last Modified:15 Nov 2021 19:45

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