Journal
ASTRONOMY & ASTROPHYSICS
Volume 666, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202243823
Keywords
techniques: photometric; instrumentation: photometers; planets and satellites: atmospheres; planets and satellites: gaseous planets; eclipses; occultations
Categories
Funding
- Spanish MINECO [AYA2017-84089]
- Swiss National Science Foundation [PCEFP2_194576, PP00P2190080, 200021_200726]
- European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project FOUR ACES) [724427]
- Swiss National Science Foundation (SNSF)
- CNES [837319]
- FCT -Fundacao para a Ciencia e a Tecnologia
- FEDER through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao [UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017, POCI-01-0145-FEDER032113, PTDC/FIS-AST/28953/2017, POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017, POCI-01-0145-FEDER-028987]
- FCT [DL 57/2016/CP1364/CT0004, CEECIND/00826/2018]
- POPH/FSE (EC)
- STFC consolidated grant [ST/R000824/1, ST/V000861/1]
- UKSA [ST/R004838/1, ST/R003203/1]
- CHEOPS ASI-INAF [2019-29-HH.0]
- Swiss National Fund [200020_172746]
- Spanish Ministry of Science and Innovation
- European Regional Development Fund [ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-87676-C5-1-R, MDM-2017-0737]
- Generalitat de Catalunya/CERCA programme
- ESA [4000124370]
- SNSA
- CNES
- Belgian Federal Science Policy Office (BELSPO)
- University of Liege through an ARC - Wallonia-Brussels Federation
- Swedish National Space Agency [DNR 65/19, 174/18]
- CRT foundation [2018.2323]
- Region Ile-de-France
- Project Equip@Meso of the programme Investissements d'Avenir [ANR-10-EQPX-29-01]
- STFC [ST/M001040/1]
- Simons Foundation [327127]
- Hungarian National Research, Development and Innovation Office (NKFIH) grant [K-125015]
- PRODEX Experiment Agreement [4000137122]
- Hungarian Academy of Science [LP2018-7/2021]
Ask authors/readers for more resources
KELT-9b is the hottest planet discovered so far, with extreme heat redistribution efficiency and a low Bond albedo. The research provides insights into the temperature variation and physical properties of the planet's atmosphere.
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).
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