CHEOPS observations of KELT-20 b/MASCARA-2 b

Autor(en): V. Singh, G. Scandariato, A. M.S. Smith, P. E. Cubillos, M. Lendl, N. Billot, A. Fortier, D. Queloz, S. G. Sousa, Sz Csizmadia, A. Brandeker, L. Carone, T. G. Wilson, B. Akinsanmi, J. A. Patel, A. Krenn, O. D.S. Demangeon, G. Bruno, I. Pagano, M. J. Hooton, J. Cabrera, N. C. Santos, Y. Alibert, R. Alonso, J. Asquier, T. Bárczy, D. Barrado Navascues, S. C.C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, M. Bergomi, A. Bonfanti, X. Bonfils, L. Borsato, C. Broeg, S. Charnoz, A. Collier Cameron, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, B. O. Demory, D. Ehrenreich, A. Erikson, L. Fossati, M. Fridlund, D. Gandolfi, M. Gillon, M. Güdel, M. N. Günther, J. V. Harre, A. Heitzmann, Ch Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, K. W.F. Lam, J. Laskar, A. Lecavelier Des Etangs, D. Magrin, P. F.L. Maxted, H. Mischler, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, E. Pallé, G. Peter, G. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, S. Salmon, D. Ségransan, A. E. Simon, M. Stalport, M. Steinberger, Gy M. Szabó, N. Thomas, S. Udry, B. Ulmer, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton, T. Zingales
Abstrakt: Context. Occultations are windows of opportunity to indirectly peek into the dayside atmosphere of exoplanets. High-precision transit events provide information on the spin-orbit alignment of exoplanets around fast-rotating hosts. Aims. We aim to precisely measure the planetary radius and geometric albedo of the ultra-hot Jupiter (UHJ) KELT-20 b along with the spin-orbit alignment of the system. Methods. We obtained optical high-precision transits and occultations of KELT-20 b using CHEOPS observations in conjunction with simultaneous TESS observations. We interpreted the occultation measurements together with archival infrared observations to measure the planetary geometric albedo and dayside temperatures. We further used the host star's gravity-darkened nature to measure the system's obliquity. Results. We present a time-averaged precise occultation depth of 82 ± 6 ppm measured with seven CHEOPS visits and 131_-7⁺⁸ from the analysis of all available TESS photometry. Using these measurements, we precisely constrain the geometric albedo of KELT-20 b to 0.26 ± 0.04 and the brightness temperature of the dayside hemisphere to 2566_-80⁺⁷⁷ K. Assuming Lambertian scattering law, we constrain the Bond albedo to 0.36_-0.05^+0.04 along with a minimal heat transfer to the night side (Ïμ = 0.14_-0.10^+0.13). Furthermore, using five transit observations we provide stricter constraints of 3 9 ± 1 1 deg on the sky-projected obliquity of the system. Conclusions. The aligned orbit of KELT-20 b is in contrast to previous CHEOPS studies that have found strongly inclined orbits for planets orbiting other A-type stars. The comparably high planetary geometric albedo of KELT-20 b corroborates a known trend of strongly irradiated planets being more reflective. Finally, we tentatively detect signs of temporal variability in the occultation depths, which might indicate variable cloud cover advecting onto the planetary day side.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): INAF-Osservatorio Astrofisico di Catania, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), INAF-Osservatorio Astrofisico di Torino, Österreichische Akademie der Wissenschaften (ÖAW), Universität Genf, Universität Bern, Eidgenössische Technische Hochschule Zürich, University of Cambridge, Universidade do Porto, Stockholm University, University of Warwick, Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna, European Space Research & Technology Centre (ESA/ESTEC), Admatis, European Space Astronomy Centre (ESA), INAF - Osservatorio Astronomico di Padova, Université Grenoble-Alpes, Université de Paris, University of St. Andrews, Lund University, Aix-Marseille Université, Université de Liège, Leiden University, Chalmers University of Technology, Università degli Studi di Torino, Technische Universität Graz, MTA Társadalomtudományi Kutatóközpont, Eötvös Loránd University Budapest, Université de recherche Paris Sciences et Lettres, Centre National De La Recherche Scientifique (CNRS), Keele University, Università degli Studi di Padova, Technische Universität Berlin, Freie Universität Berlin (FU), Spanish National Research Council (CSIC), Institut d'Estudis Espacials de Catalunya (IEEC), HUN-REN Magyar Kutatási Hálózat
Journal: Astronomy and Astrophysics
Band: 683
Anzahl der Seiten: 25
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/202347533
Publikationsdatum: 03-2024
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik, 103038 Weltraumforschung
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/72cc124c-c63b-4443-9ebc-db246bf14bc1

Zurück