Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS

Autor(en)

J. A. Egger, H. P. Osborn, D. Kubyshkina, C. Mordasini, Y. Alibert, M. N. Günther, M. Lendl, A. Brandeker, A. Heitzmann, A. Leleu, M. Damasso, A. Bonfanti, T. G. Wilson, S. G. Sousa, J. Haldemann, L. Delrez, M. J. Hooton, T. Zingales, R. Luque, R. Alonso, J. Asquier, T. Bárczy, D. Barrado Navascues, S. C.C. Barros, W. Baumjohann, W. Benz, N. Billot, L. Borsato, C. Broeg, M. Buder, A. Castro-González, A. Collier Cameron, A. C.M. Correia, D. Cortes, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, O. D.S. Demangeon, B. O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, K. Gazeas, M. Gillon, M. Güdel, Ch Helling, K. G. Isaak, L. L. Kiss, J. Korth, K. W.F. Lam, J. Laskar, B. Lavie, A. Lecavelier des Etangs, C. Lovis, A. Luntzer, D. Magrin, P. F.L. Maxted, B. Merín, M. Munari, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, J. Rodrigues, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M.S. Smith, M. Stalport, S. Sulis, Gy M. Szabó, S. Udry, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton

Abstrakt

Multiplanetary systems spanning the radius valley are ideal testing grounds for exploring the different proposed explanations for the observed bimodality in the radius distribution of close-in exoplanets. One such system is HIP 29442 (TOI-469), an evolved K0V star hosting two super-Earths and one sub-Neptune. We observed HIP 29442 with CHEOPS for a total of 9.6 days, which we modelled jointly with two sectors of TESS data to derive planetary radii of 3.410 ± 0.046, 1.551 ± 0.045, and 1.538 ± 0.049 R? for planets b, c, and d, which orbit HIP 29442 with periods of 13.6, 3.5, and 6.4 days, respectively. For planet d this value deviates by more than 3s from the median value reported in the discovery paper, leading us to conclude that caution is required when using TESS photometry to determine the radii of small planets with low per-transit signal-to-noise ratios and large gaps between observations. Given the high precision of these new radii, combining them with published RVs from ESPRESSO and HIRES provides us with ideal conditions to investigate the internal structure and formation pathways of the planets in the system. We introduced the publicly available code plaNETic, a fast and robust neural network-based Bayesian internal structure modelling framework. We then applied hydrodynamic models to explore the upper atmospheric properties of these inferred structures. Finally, we identified planetary system analogues in a synthetic population generated with the Bern model for planet formation and evolution. Based on this analysis, we find that the planets likely formed on opposing sides of the water iceline from a protoplanetary disk with an intermediate solid mass. We finally report that the observed parameters of the HIP 29442 system are compatible with a scenario where the second peak in the bimodal radius distribution corresponds to sub-Neptunes with a pure H/He envelope and with a scenario with water-rich sub-Neptunes.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Universität Bern, Massachusetts Institute of Technology, Österreichische Akademie der Wissenschaften (ÖAW), European Space Research & Technology Centre (ESA/ESTEC), Universität Genf, Stockholm University, INAF-Osservatorio Astrofisico di Torino, University of Warwick, Universidade do Porto, Université de Liège, Katholieke Universiteit Leuven, University of Cambridge, Università degli Studi di Padova, INAF - Osservatorio Astronomico di Padova, University of Chicago, Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna, Admatis, Centro de Astrobiología (CSIC-INTA), Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), University of St. Andrews, Universidade de Coimbra, Airbus Defence and Space, Lund University, Aix-Marseille Université, Eötvös Loránd University Budapest, SRON Netherlands Institute for Space Research , Leiden University, Chalmers University of Technology, Università degli Studi di Torino, National & Kapodistrian University of Athens, Technische Universität Graz, HUN-REN Magyar Kutatási Hálózat, 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, Freie Universität Berlin (FU), Spanish National Research Council (CSIC), Institut d'Estudis Espacials de Catalunya (IEEC)

Journal

Astronomy and Astrophysics

Band

688

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/202450472

Publikationsdatum

08-2024

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/a0445dca-e44e-483f-a0f4-f25c0b332892