CHEOPS geometric albedo of the hot Jupiter HD 209458 b

Brandeker, A.; Heng, K.; Lendl, M.; Patel, J. A.; Morris, B. M.; Broeg, C.; Guterman, P.; Beck, M.; Maxted, P. F. L.; Demangeon, O.; Delrez, L.; Demory, B.-O.; Kitzmann, D.; Santos, N. C.; Singh, V.; Alibert, Y.; Alonso, R.; Anglada, G.; Bárczy, T.; Barrado y Navascues, D.; ... (2022). CHEOPS geometric albedo of the hot Jupiter HD 209458 b. Astronomy and astrophysics, 659, L4. EDP Sciences 10.1051/0004-6361/202243082

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We report the detection of the secondary eclipse of the hot Jupiter HD 209458 b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4−3.3+3.2 parts per million translates into a geometric albedo of Ag = 0.096 ± 0.016. The previously estimated dayside temperature of about 1500 K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of Ag for any exoplanet. Our calculations of the bandpass-integrated geometric albedo demonstrate that the measured value of Ag is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, and the water and sodium abundances are consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458 b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud free.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Heng, Kevin, Morris, Brett Michael, Broeg, Christopher, Demory, Brice-Olivier Denys, Kitzmann, Daniel, Alibert, Yann Daniel Pierre, Beck, Thomas, Benz, Willy, Fortier, A., Thomas, Nicolas

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Brice-Olivier Denys Demory

Date Deposited:

04 Apr 2022 09:57

Last Modified:

02 Mar 2023 23:36

Publisher DOI:

10.1051/0004-6361/202243082

BORIS DOI:

10.48350/168377

URI:

https://boris.unibe.ch/id/eprint/168377

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