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Thermal Phase Curves of XO-3b: An Eccentric Hot Jupiter at the Deuterium Burning Limit

Dang, Lisa and Bell, Taylor J. and Cowan, Nicolas B. and Thorngren, Daniel and Kataria, Tiffany and Knutson, Heather A. and Lewis, Nikole K. and Stassun, Keivan G. and Fortney, Jonathan J. and Agol, Eric and Laughlin, Gregory P. and Burrows, Adam and Collins, Karen A. and Deming, Drake and Jovmir, Diana and Langton, Jonathan and Rastegar, Sara and Showman, Adam P. (2022) Thermal Phase Curves of XO-3b: An Eccentric Hot Jupiter at the Deuterium Burning Limit. Astronomical Journal, 163 (1). Art. No. 32. ISSN 0004-6256. doi:10.3847/1538-3881/ac365f.

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We report Spitzer full-orbit phase observations of the eccentric hot Jupiter XO-3b at 3.6 and 4.5 μm. Our new eclipse depth measurements of 1770 ± 180 ppm at 3.6 μm and 1610 ± 70 ppm at 4.5 μm show no evidence of the previously reported dayside temperature inversion. We also empirically derive the mass and radius of XO-3b and its host star using Gaia DR3's parallax measurement and find a planetary mass M_p = 11.79 ± 0.98 M_(Jup) and radius R_p = 1.295 ± 0.066 R_(Jup). We compare our Spitzer observations with multiple atmospheric models to constrain the radiative and advective properties of XO-3b. While the decorrelated 4.5 μm observations are pristine, the 3.6 μm phase curve remains polluted with detector systematics due to larger amplitude intrapixel sensitivity variations in this channel. We focus our analysis on the more reliable 4.5 μm phase curve and fit an energy balance model with solid body rotation to estimate the zonal wind speed and the pressure of the bottom of the mixed layer. Our energy balance model fit suggests an eastward equatorial wind speed of 3.13^(+0.26)_(−0.83) km s⁻¹, an atmospheric mixed layer down to 2.40^(+0.92)_(−0.16) bars, and a Bond albedo of 0.106^(+0.008)_(−0.106). We assume that the wind speed and mixed layer depth are constant throughout the orbit. We compare our observations with 1D planet-averaged model predictions at apoapse and periapse and 3D general circulation model predictions for XO-3b. We also investigate the inflated radius of XO-3b and find that it would require an unusually large amount of internal heating to explain the observed planetary radius.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Dang, Lisa0000-0003-4987-6591
Bell, Taylor J.0000-0003-4177-2149
Cowan, Nicolas B.0000-0001-6129-5699
Thorngren, Daniel0000-0002-5113-8558
Kataria, Tiffany0000-0003-3759-9080
Knutson, Heather A.0000-0002-5375-4725
Lewis, Nikole K.0000-0002-8507-1304
Stassun, Keivan G.0000-0002-3481-9052
Fortney, Jonathan J.0000-0002-9843-4354
Agol, Eric0000-0002-0802-9145
Laughlin, Gregory P.0000-0002-3253-2621
Burrows, Adam0000-0002-3099-5024
Collins, Karen A.0000-0001-6588-9574
Deming, Drake0000-0001-5727-4094
Additional Information:© 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 July 28; revised 2021 October 25; accepted 2021 October 30; published 2021 December 22. L.D. acknowledges support in part through the Technologies for Exo-Planetary Science (TEPS) PhD Fellowship (NSERC: CREATE 4826) and the Natural Sciences and Engineering Research Council of Canada (NSERC) Postgraduate Scholarships Doctoral Fellowship (NSERC: PGSD 534218-2019). This work is based on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. T.J.B. acknowledges support from the McGill Space Institute Graduate Fellowship, the Natural Sciences and Engineering Research Council of Canada's Postgraduate Scholarships Doctoral Fellowship (NSERC: PGSD 519511-2018), and from the Fonds de recherche du Québec—Nature et technologies through the Centre de recherche en astrophysique du Québec. Facility: Spitzer Space Telescope (IRAC) - . Software: astropy (Astropy Collaboration et al. 2013), emcee (Foreman-Mackey et al. 2013), batman (Kreidberg2015), SPCA (Dang et al. 2018; Bell et al. 2021), Bell_EBM (Bell & Cowan 2018).
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)CREATE 4826
Natural Sciences and Engineering Research Council of Canada (NSERC)PGSD 534218-2019
McGill Space InstituteUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)519511-2018
Fonds de recherche du Québec - Nature et technologies (FRQNT)UNSPECIFIED
Subject Keywords:Exoplanet atmospheres; Exoplanet astronomy; Exoplanet tides; Exoplanets; Exoplanet systems
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Exoplanet astronomy (486); Exoplanet tides (497); Exoplanets (498); Exoplanet systems (484)
Record Number:CaltechAUTHORS:20220110-724957400
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Official Citation:Lisa Dang et al 2022 AJ 163 32
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112810
Deposited By: Tony Diaz
Deposited On:10 Jan 2022 23:04
Last Modified:10 Jan 2022 23:04

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