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 similar to 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% (1 sigma).

The stable climate of KELT-9b

D. Gandolfi;
2022-01-01

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 similar to 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% (1 sigma).
2022
Inglese
Esperti anonimi
666
1
19
19
https://www.aanda.org/articles/aa/full_html/2022/10/aa43823-22/aa43823-22.html
techniques: photometric; instrumentation: photometers; planets and satellites: atmospheres; planets and satellites: gaseous planets; eclipses; occultations
   GANDOLFI D. - Fondaz.CRT - II tornata 2018 - Rif. 2018.2323 - "Gaseous or rocky? Unveiling the nature of small worlds"
   FONDAZIONE CRT
   Rif. 2018.2323
4 – prodotto già presente in altro archivio Open Access (arXiv, REPEC…)
262
79
K. Jones; B. M. Morris; B.-O. Demory; K. Heng; M. J. Hooton; N. Billot; D. Ehrenreich; S. Hoyer; A. E. Simon; M. Lendl; O. D. S. Demangeon; S. G. Sous...espandi
info:eu-repo/semantics/article
open
03-CONTRIBUTO IN RIVISTA::03A-Articolo su Rivista
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1948620
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