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The stable climate of KELT-9b

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  • Additional Information
    • Publication Information:
      EDP Sciences
    • Publication Date:
      2022
    • Collection:
      BORIS (Bern Open Repository and Information System, University of Bern)
    • Abstract:
      Even among the most irradiated gas giants, so-called ultra-hot Jupiters, KELT-9b stands out as the hottest planet thus far discovered with a dayside temperature of over 4500 K. At these extreme irradiation levels, we expect an increase in heat redistribution efficiency and a low Bond albedo owed to an extended atmosphere with molecular hydrogen dissociation occurring on the planetary dayside. We present new photometric observations of the KELT-9 system throughout 4 full orbits and 9 separate occultations obtained by the 30 cm space telescope CHEOPS. The CHEOPS bandpass, located at optical wavelengths, captures the peak of the thermal emission spectrum of KELT-9b. In this work we simultaneously analyse CHEOPS phase curves along with public phase curves from TESS and Spitzer to infer joint constraints on the phase curve variation, gravity-darkened transits, and occultation depth in three bandpasses, as well as derive 2D temperature maps of the atmosphere at three different depths. We find a day-night heat redistribution efficiency of ~0.3 which confirms expectations of enhanced energy transfer to the planetary nightside due to dissociation and recombination of molecular hydrogen. We also calculate a Bond albedo consistent with zero. We find no evidence of variability of the brightness temperature of the planet, excluding variability greater than 1%
    • File Description:
      application/pdf
    • Relation:
      https://boris.unibe.ch/180446/
    • Online Access:
      https://boris.unibe.ch/180446/1/aa43823-22.pdf
      https://boris.unibe.ch/180446/
    • Rights:
      info:eu-repo/semantics/openAccess
    • Accession Number:
      edsbas.57A01190