The K2-24 planetary system revisited by CHEOPS

Author(s): V. Nascimbeni, L. Borsato, P. Leonardi, S. G. Sousa, T. G. Wilson, A. Fortier, A. Heitzmann, G. Mantovan, R. Luque, T. Zingales, G. Piotto, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado Navascues, S. C.C. Barros, W. Baumjohann, T. Beck, W. Benz, N. Billot, F. Biondi, A. Brandeker, C. Broeg, M. D. Busch, A. Collier Cameron, A. C.M. Correia, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D.S. Demangeon, B. O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, L. Fossati, M. Fridlund, D. Gandolfi, K. Gazeas, M. Gillon, M. Güdel, M. N. Günther, Ch Helling, K. G. Isaak, F. Kerschbaum, L. L. Kiss, J. Korth, K. W.F. Lam, J. Laskar, A. Lecavelier Des Etangs, A. Leleu, M. Lendl, D. Magrin, P. F.L. Maxted, B. Merín, C. Mordasini, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, 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, R. Southworth, M. Stalport, S. Sulis, Gy M. Szabó, S. Udry, B. Ulmer, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton
Abstract: The planetary system K2-24 is composed of two transiting low-density Neptunians locked in an almost perfect 2:1 resonance and showing large transit time variations (TTVs), and it is an excellent laboratory to search for signatures of planetary migration. Previous studies performed with K2, Spitzer, and RV data tentatively claimed a significant non-zero eccentricity for one or both planets, possibly high enough to challenge the scenario of pure disk migration through resonant capture. With 13 new CHEOPS light curves (seven of planet b, six of planet c), we carried out a global photometric and dynamical re-analysis by including all the available literature data as well. We obtained the most accurate set of planetary parameters to date for the K2-24 system, including radii and masses at 1% and 5% precision (now essentially limited by the uncertainty on stellar parameters) and non-zero eccentricities e_b = 0.0498_-0.0018^+0.0011, e_c = 0.0282_-0.0007^+0.0003 detected at very high significance for both planets. Such relatively large values imply the need for an additional physical mechanism of eccentricity excitation during or after the migration stage. Also, while the accuracy of the previous TTV model had drifted by up to 0.5 days at the current time, we constrained the orbital solution firmly enough to predict the forthcoming transits for the next ~15 years, thus enabling efficient follow-up with top-level facilities such as JWST or ESPRESSO.
Organisation(s): Department of Astrophysics
External organisation(s): Osservatorio Astronomico, University of Padova, Università degli Studi di Trento, Universidade do Porto, University of Warwick, Universität Bern, Université de Genève, University of Chicago, Institute of Astrophysics of the Canary Islands, University of La Laguna, Admatis Ltd., Centro de Astrobiología (CSIC-INTA), Österreichische Akademie der Wissenschaften (ÖAW), Max-Planck-Institut für extraterrestrische Physik, Stockholm University, University of St. Andrews, Universidade de Coimbra, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), INAF-Osservatorio Astrofisico di Torino, Lund University, Aix-Marseille Université, Université de Liège, Katholieke Universiteit Leuven, Eötvös Loránd University Budapest, SRON Netherlands Institute for Space Research , Leiden University, Chalmers University of Technology, University of Turin, National & Kapodistrian University of Athens, Science and Operations Department - Science Division (SCI-SC), Technische Universität Graz, Eötvös Loránd Research Network, Lund Observatory, Université de recherche Paris Sciences et Lettres, Université Paris VI - Pierre-et-Marie-Curie, Keele University, European Space Astronomy Centre (ESA), INAF-Osservatorio Astrofisico di Catania, Eidgenössische Technische Hochschule Zürich, University of Cambridge, Freie Universität Berlin (FU), Spanish National Research Council (CSIC), Institute of Space Studies of Catalonia (IEEC), European Space Agency (ESOC) Germany, HUN-REN Hungarian Research Network
Journal: Astronomy and Astrophysics
Volume: 690
No. of pages: 16
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/202450852
Publication date: 10-2024
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/1d1126d1-14fb-485a-8818-44a90fd41713

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