Characterization of the HD 108236 system with CHEOPS and TESS Confirmation of a fifth transiting planet

Autor(en)

Sergio Hoyer, A. Bonfanti, A. Leleu, L. Acuna, Luisa Maria Serrano, Manuel Güdel, A. Bekkelien, Christopher Broeg, Hans-Gustav Florén, Didier Queloz, Thomas G. Wilson, S. G. Sousa, M. J. Hooton, V. Adibekyan, Yann Alibert, Claudio R. Alonso, G. Anglada, J. Asquier, T. Bárczy, David Barrado, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi, X. Bonfils, A. Brandeker, Juan Cabrera, S. Charnoz, A. Collier Cameron, Szilard Csizmadia, M. B. Davies, L. Delrez, O. D. S. Demangeon, B. O. Demory, D. Ehrenreich, Anders Erikson, A. Fortier, L. Fossati, M. Fridlund, Davide Gandolfi, Michael Gillon, Manuel Güdel, N. C. Hara, Kevin Heng, K. G. Isaak, Jon M. Jenkins, Laszlo Kiss, J. Laskar, D. W. Latham, Alain Lecavelier Des Etangs, M. Lendl, Christophe Lovis, Armin Luntzer, D. Magrin, P. F. L. Maxted, Valerio Nascimbeni, Göran Olofsson, Roland Ottensamer, Isabella Pagano, E. Pallé, C. M. Persson, G. Peter, D. Piazza, Giampaolo P. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, Heike Rauer, Ignasi Ribas, George R. Ricker, S. Salmon, Nuno C. Santos, Gaetano Scandariato, Sara Seager, Damien Ségransan, A. E. Simon, A. M. S. Smith, Manfred Steller, Gy M. Szabó, N. Thomas, Joseph D. Twicken, Stephane Udry, Valerie Van Grootel, Roland K. Vanderspek, N. A. Walton, K. Westerdorff, Joshua N. Winn

Abstrakt

Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 Ro˙). Aims. We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. Methods. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets' physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD 108236 to search for the presence of transit timing variations. Results. We derived improved values for the radius and mass of the host star (R∗ = 0.876 ± 0.007 R0 and M∗ = 0.867-0.046+0.047M). We confirm the presence of the fifth transiting planet f in a 29.54 d orbit. Thus, the HD 108236 system consists of five planets of Rb = 1.587±0.028, Rc = 2.122±0.025, Rd = 2.629 ± 0.031, Re = 3.008 ± 0.032, and Rf = 1.89 ± 0.04 [Ro˙]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. Conclusions. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9 d orbital period, as previously suggested. Further monitoring of the transits, particularly for planets b and f, would confirm the presence of the observed transit time variations. HD 108236 thus becomes a key multi-planetary system for the study of formation and evolution processes. The reported precise results on the planetary radii - together with a profuse RV monitoring - will allow for an accurate characterization of the internal structure of these planets.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Universität Bern, Università degli Studi di Torino, University of Cambridge, Stockholm University, University of St. Andrews, Spanish National Research Council (CSIC), Instituto de Astrofísica de Canarias (IAC), Institut d'Estudis Espacials de Catalunya (IEEC), European Space Research & Technology Centre (ESA/ESTEC), Admatis, Universidade do Porto, INAF - Osservatorio Astronomico di Padova, Université Grenoble-Alpes, Université de Paris, Aix-Marseille Université, Universität Genf, Lund University, Harvard-Smithsonian Center for Astrophysics, Icm & Sorbonne University, Österreichische Akademie der Wissenschaften (ÖAW), Eidgenössische Technische Hochschule Zürich, Universidad de La Laguna, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Université de Liège, Leiden University, Chalmers University of Technology, University of Warwick, National Aeronautics & Space Administration (NASA), Magyar Tudományos Akadémia, Eötvös Loránd University Budapest, Université Paris IV - Paris-Sorbonne, Observatoire de Paris, Keele University, INAF-Osservatorio Astrofisico di Catania, Università degli Studi di Padova, Technische Universität Berlin, Massachusetts Institute of Technology, Max-Planck-Institut für extraterrestrische Physik, Freie Universität Berlin (FU), SETI Institute, NASA Ames Research Center

Journal

Astronomy & Astrophysics

Band

668

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/202243720

Publikationsdatum

12-2022

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/d3de861c-5a24-4d96-b728-33296010f00c