Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022
EPSC Abstracts
Vol. 16, EPSC2022-697, 2022
Europlanet Science Congress 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

CHEOPS Geometric albedo measurements of benchmark hot Jupiters

Andreas Krenn1,2, Monika Lendl2, and Alexis Brandeker3
Andreas Krenn et al.
  • 1Space Research Institute, Austrian Academy of Sciences, Graz, Austria (
  • 2Observatory of the University of Geneva, University of Geneva, Versoix, Switzerland
  • 3Institute of Astronomy, Stockholm University, Stockholm, Sweden

By measuring the geometric albedo of a planet, the reflectivity of its atmosphere can be determined. This constitutes a vital piece of information when trying to characterise the nature of the planetary atmosphere. The albedo of a planet can be determined by measuring the drop in observed stellar flux when the planet is occulted by its host star during secondary eclipse.

We present observations of secondary eclipses of the gas giants HD189733b and HD209458b at optical wavelengths performed by the Characterising Exoplanets Satellite (CHEOPS). As both planets have moderate temperatures, the thermal contribution to their eclipse depth in the optical is small, making our observations uniquely sensitive to the reflectivity of the planetary atmospheres. Our data thus allow precise measurements of the planets’ geometric albedos, which we will present here. We will further discuss our findings and their implications in terms of the planetary atmospheric composition and the possible presence of aerosols. Finally, we compare our results with those of similar studies and discuss the implications of our findings in the context of future observations characterising gas giant atmospheres. 

How to cite: Krenn, A., Lendl, M., and Brandeker, A.: CHEOPS Geometric albedo measurements of benchmark hot Jupiters, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-697,, 2022.


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