Refined parameters of the HD 22946 planetary system and the true orbital period of planet d

Autor(en): Z. Garai, H. P. Osborn, D. Gandolfi, A. Brandeker, S. G. Sousa, M. Lendl, A. Bekkelien, C. Broeg, A. Collier Cameron, J. A. Egger, M. J. Hooton, Y. Alibert, L. Delrez, L. Fossati, S. Salmon, T. G. Wilson, A. Bonfanti, A. Tuson, S. Ulmer-Moll, L. M. Serrano, L. Borsato, R. Alonso, G. Anglada, J. Asquier, D. Barrado Y Navascues, S. C.C. Barros, T. Bárczy, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi, X. Bonfils, M. Buder, J. Cabrera, V. Cessa, S. Charnoz, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, O. D.S. Demangeon, B. O. Demory, D. Ehrenreich, A. Erikson, V. Van Eylen, A. Fortier, M. Fridlund, M. Gillon, V. Van Grootel, M. Güdel, M. N. Günther, S. Hoyer, K. G. Isaak, L. L. Kiss, M. H. Kristiansen, J. Laskar, A. Lecavelier Des Etangs, C. Lovis, A. Luntzer, D. Magrin, P. F.L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M.S. Smith, M. Steller, Gy M. Szabó, N. Thomas, S. Udry, J. Venturini, N. Walton
Abstrakt: Context. Multi-planet systems are important sources of information regarding the evolution of planets. However, the long-period planets in these systems often escape detection. These objects in particular may retain more of their primordial characteristics compared to close-in counterparts because of their increased distance from the host star. HD 22946 is a bright (G = 8.13 mag) late F-type star around which three transiting planets were identified via Transiting Exoplanet Survey Satellite (TESS) photometry, but the true orbital period of the outermost planet d was unknown until now. Aims. We aim to use the Characterising Exoplanet Satellite (CHEOPS) space telescope to uncover the true orbital period of HD 22946d and to refine the orbital and planetary properties of the system, especially the radii of the planets. Methods. We used the available TESS photometry of HD 22946 and observed several transits of the planets b, c, and d using CHEOPS. We identified two transits of planet d in the TESS photometry, calculated the most probable period aliases based on these data, and then scheduled CHEOPS observations. The photometric data were supplemented with ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) radial velocity data. Finally, a combined model was fitted to the entire dataset in order to obtain final planetary and system parameters. Results. Based on the combined TESS and CHEOPS observations, we successfully determined the true orbital period of the planet d to be 47.42489 ± 0.00011 days, and derived precise radii of the planets in the system, namely 1.362 ± 0.040 R, 2.328 ± 0.039 R, and 2.607 ± 0.060 R for planets b, c, and d, respectively. Due to the low number of radial velocities, we were only able to determine 3σ upper limits for these respective planet masses, which are 13.71 M, 9.72 M, and 26.57 M. We estimated that another 48 ESPRESSO radial velocities are needed to measure the predicted masses of all planets in HD 22946. We also derived stellar parameters for the host star. Conclusions. Planet c around HD 22946 appears to be a promising target for future atmospheric characterisation via transmission spectroscopy. We can also conclude that planet d, as a warm sub-Neptune, is very interesting because there are only a few similar confirmed exoplanets to date. Such objects are worth investigating in the near future, for example in terms of their composition and internal structure.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Eötvös Loránd University Budapest, Slovenian Academy of Sciences and Arts, Universität Bern, Massachusetts Institute of Technology, Università degli Studi di Torino, Stockholm University, Universidade do Porto, Universität Genf, University of St. Andrews, University of Cambridge, Université de Liège, Österreichische Akademie der Wissenschaften (ÖAW), INAF - Osservatorio Astronomico di Padova, Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna, Institut d'Estudis Espacials de Catalunya (IEEC), Spanish National Research Council (CSIC), European Space Research & Technology Centre (ESA/ESTEC), European Space Astronomy Centre (ESA), Admatis, Max-Planck-Institut für extraterrestrische Physik, Université Grenoble-Alpes, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Université de Paris, INAF-Osservatorio Astrofisico di Torino, Lund University, Aix-Marseille Université, University College London, Leiden University, Chalmers University of Technology, MTA Társadalomtudományi Kutatóközpont, Brorfelde Observatory, Université de recherche Paris Sciences et Lettres, Université Paris VI - Pierre-et-Marie-Curie, Keele University, INAF-Osservatorio Astrofisico di Catania, Università degli Studi di Padova, University of Warwick, Technische Universität Berlin
Journal: Astronomy and Astrophysics
Band: 674
Anzahl der Seiten: 14
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/202345943
Publikationsdatum: 06-2023
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/8838bafa-5e1d-4ced-aaa8-a08dee5cf732

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