The K2-24 planetary system revisited by CHEOPS

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.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2024-09-16
DOI
https://doi.org/10.1051/0004-6361/202450852
Citations
5
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
2.53

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article

The K2-24 planetary system revisited by CHEOPS

M. Stalport, T. Bárczy, M. Gy. Szabó, A. Collier Cameron et al.
5 citations
Astronomy and Astrophysics
Astronomy and Astrophysical Research
2.53
article

The K2-24 planetary system revisited by CHEOPS

M. Stalport, T. Bárczy, M. Gy. Szabó, A. Collier Cameron, N. Billot, H. Rauer, Y. Alibert, A. M. S. Smith, R. Ottensamer, J. Laskar, Maximilian N. Günther, S. Sulis, R. Luque, Richard Southworth, L. Borsato, M. Gillon, P. F. L. Maxted, V. Nascimbeni, M. Lendl, A. Erikson, L. L. Kiss, D. Ségransan, D. Gandolfi, D. Queloz, D. Pollacco, A. C. M. Correia, C. Mordasini, J. Korth, A. Leleu, A. E. Simon, G. Piotto, B. Edwards, M. B. Davies, T. Zingales, P. Leonardi, R. Alonso, G. Peter, Roberto Ragazzoni, A. Fortier, A. Derekas, F. Kerschbaum, F. Biondi, I. Ribas, K. W. F. Lam, K. G. Isaak, G. Mantovan, Ch. Helling, C. Broeg, M. Güdel, A. Heitzmann, G. Scandariato, D. Barrado, N. A. Walton, S. Udry, M. Deleuil, W. Baumjohann, S. C. C. Barros, L. Delrez, W. Benz, E. Villaver, N. C. Santos, Patricio E. Cubillos, Demetrio Magrin, K. Gazeas, J. Venturini, G. Olofsson, Brice-Olivier Demory, L. Fossati, D. Ehrenreich, A. Deline, M. Fridlund, A. Brandeker, T. G. Wilson, B. Merín, V. Van Grootel, S. G. Sousa, A. Lecavelier des Etangs, N. Rando, O. D. S. Demangeon, M.-D. Busch, B. Ulmer, Sz. Csizmadia, T. Beck, E. Pallé, I. Pagano
article en
5 citations

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.

Astronomy and AstrophysicsVol. 690
Eötvös Loránd University (HU), University of Geneva (CH), University of Bern (CH), Leiden University (NL), Centre National de la Recherche Scientifique (FR), University of Vienna (AT), European Space Operations Centre (DE), Institute of Space Sciences (ES), Austrian Academy of Sciences (AT), University of Padua (IT), University of Liège (BE), Universidad de La Laguna (ES), Stockholm University (SE), University of St Andrews (GB), Universidade do Porto (PT), Lund University (SE), University of Trento (IT), National and Kapodistrian University of Athens (GR), University of Miskolc (HU), Aix-Marseille Université (FR), University of Cambridge (GB), Institut d'Astrophysique de Paris (FR), Konkoly Observatory (HU), Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE), ETH Zurich (CH), University of Warwick (GB), Sorbonne Université (FR), University of Chicago (US), Graz University of Technology (AT), Institute of Astrophysics and Space Sciences (PT), Space Research Institute (AT), Max Planck Institute for Extraterrestrial Physics (DE), Institut d'Estudis Espacials de Catalunya (ES), European Space Astronomy Centre (ES), Osservatorio Astrofisico di Torino (IT), Cavendish Hospital (GB), Institute of Astronomy (RU), Osservatorio Astrofisico di Catania (IT), HUN-REN Research Centre for Astronomy and Earth Sciences (HU), Centro de Astrobiología (ES), Instituto de Astrofísica de Canarias (ES), AlbaNova (SE), Szent Imre Egyetemi Oktatókórház (HU), Osservatorio Astronomico di Padova (IT), Leiden Observatory, European Space Research and Technology Centre (NL), Space Research Organisation Netherlands (NL), Institut de Mécanique Céleste et de Calcul des Éphémérides (FR), University of Turin (IT), Keele University (GB), Chalmers University of Technology (SE), Freie Universität Berlin (DE), University of Coimbra (PT), KU Leuven (BE)
National Science Foundation, Fondazione CRT, UK Space Agency, Ministerio de Ciencia, Innovación y Universidades, Centres de Recerca de Catalunya, European Space Agency, University of Warwick, European Commission, Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Swedish National Space Agency, Austrian Science Fund, Fonds De La Recherche Scientifique - FNRS, Belgian Federal Science Policy Office, Generalitat de Catalunya, Centre National d’Etudes Spatiales, Università degli Studi di Trento, Ministerio de Ciencia e Innovación, Université de Liège, Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, Instituto de Astrofísica de Canarias, Horizon 2020 Framework Programme, Science and Technology Facilities Council, Fundação para a Ciência e a Tecnologia, Staatssekretariat für Bildung, Forschung und Innovation, European Regional Development Fund, Agencia Estatal de Investigación, National Research, Development and Innovation Office
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