Hints of a close outer companion to the ultra-hot Jupiter TOI-2109 b

Autor(en)

J. V. Harre, A. M.S. Smith, S. C.C. Barros, V. Singh, J. Korth, A. Brandeker, A. Collier Cameron, M. Lendl, T. G. Wilson, L. Borsato, Sz Csizmadia, J. Cabrera, H. Parviainen, A. C.M. Correia, B. Akinsanmi, N. Rosario, P. Leonardi, L. M. Serrano, Y. Alibert, R. Alonso, J. Asquier, T. Bárczy, D. Barrado Navascues, W. Baumjohann, W. Benz, N. Billot, C. Broeg, M. D. Busch, 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, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, K. Gazeas, M. Gillon, M. Güdel, M. N. Günther, A. Heitzmann, Ch Helling, K. G. Isaak, L. L. Kiss, K. W.F. Lam, J. Laskar, A. Lecavelier des Etangs, D. Magrin, P. F.L. Maxted, B. Merín, C. Mordasini, 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, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, S. G. Sousa, M. Stalport, S. Sulis, Gy M. Szabó, S. Udry, B. Ulmer, V. Van Grootel, J. Venturini, E. Villaver, V. Viotto, N. A. Walton, R. West, K. Westerdorff

Abstrakt

Context. Hot Jupiters (HJs) with close-by planetary companions are rare, with only a handful of them having been discovered so far. This could be due to their suggested dynamical histories, which lead to the possible ejection of other planets. TOI-2109 b is special in this regard because it is the HJ with the closest relative separation from its host star, being separated by less than 2.3 stellar radii. Unexpectedly, transit timing measurements from recently obtained CHEOPS observations show low-amplitude transit-timing variations (TTVs). Aims. We aim to search for signs of orbital decay and to characterise the apparent TTVs in an attempt to gain information about a possible companion. Methods. We fitted the newly obtained CHEOPS light curves using TLCM and extracted the resulting mid-transit timings. Successively, we used these measurements in combination with TESS and archival photometric data and radial velocity (RV) data to estimate the rate of tidal orbital decay of TOI-2109 b, and also to characterise the TTVs using the N-body code TRADES and the photo-dynamical approach of PyTTV. Results. We find tentative evidence at 3σ for orbital decay in the TOI-2109 system when we correct the mid-transit timings using the best-fitting sinusoidal model of the TTVs. We do not detect additional transits in the available photometric data, but find evidence supporting the authenticity of the apparent TTVs, indicating a close-by, outer companion with P_c > 1.125 d. Due to the fast rotation of the star, the new planetary candidate cannot be detected in the available RV measurements, and its parameters can only be loosely constrained by our joint TTV and RV modelling. Conclusions. TOI-2109 could join a small group of rare HJ systems that host close-by planetary companions, only one of which (WASP-47 b) has an outer companion. More high-precision photometric measurements are necessary to confirm the existence of this planetary companion.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Universidade do Porto, INAF-Osservatorio Astrofisico di Catania, Lund Observatory, Stockholm University, University of St. Andrews, Universität Genf, University of Warwick, INAF - Osservatorio Astronomico di Padova, Instituto de Astrofísica de Canarias (IAC), Universidade de Coimbra, Università degli Studi di Padova, Università degli Studi di Torino, Universität Bern, Universidad de La Laguna, European Space Research & Technology Centre (ESA/ESTEC), Admatis, European Space Astronomy Centre (ESA), Österreichische Akademie der Wissenschaften (ÖAW), 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, National & Kapodistrian University of Athens, Technische Universität Graz, MTA Társadalomtudományi Kutatóközpont, Université de recherche Paris Sciences et Lettres, Université Paris VI - Pierre-et-Marie-Curie, Keele University, Eidgenössische Technische Hochschule Zürich, University of Cambridge, 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

692

Anzahl der Seiten

21

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/202451068

Publikationsdatum

12-2024

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/b16cd882-435e-4c3f-8c5a-7a480ae5e5ad