TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906

Autor(en): A. Tuson, D. Queloz, H. P. Osborn, T. G. Wilson, M. J. Hooton, M. Beck, M. Lendl, G. Olofsson, A. Fortier, A. Bonfanti, A. Brandeker, L. A. Buchhave, A. Collier Cameron, D. R. Ciardi, K. A. Collins, D. Gandolfi, Z. Garai, S. Giacalone, J. Gomes da Silva, S. B. Howell, J. A. Patel, C. M. Persson, L. M. Serrano, S. G. Sousa, S. Ulmer-Moll, A. Vanderburg, C. Ziegler, Y. Alibert, R. Alonso, G. Anglada, T. Bárczy, D. Barrado Navascues, S. C.C. Barros, W. Baumjohann, T. Beck, W. Benz, N. Billot, X. Bonfils, L. Borsato, C. Broeg, J. Cabrera, S. Charnoz, D. M. Conti, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, L. Delrez, O. D.S. Demangeon, B. O. Demory, D. Dragomir, C. D. Dressing, D. Ehrenreich, A. Erikson, Z. Essack, J. Farinato, L. Fossati, M. Fridlund, E. Furlan, H. Gill, M. Gillon, C. L. Gnilka, E. Gonzales, M. Güdel, M. N. Günther, S. Hoyer, K. G. Isaak, J. M. Jenkins, L. L. Kiss, J. Laskar, D. W. Latham, N. Law, A. Lecavelier des Etangs, G. Lo Curto, C. Lovis, R. Luque, D. Magrin, A. W. Mann, P. F.L. Maxted, M. Mayor, S. McDermott, M. Mecina, C. Mordasini, A. Mortier, V. Nascimbeni, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, T. Pritchard, R. Ragazzoni, N. Rando, F. Ratti, H. Rauer, I. Ribas, G. R. Ricker, M. Rieder, N. C. Santos, A. B. Savel, G. Scandariato, R. P. Schwarz, S. Seager, D. Ségransan, A. Shporer, A. E. Simon, A. M.S. Smith, M. Steller, C. Stockdale, Gy M. Szabó, N. Thomas, G. Torres, R. Tronsgaard, S. Udry, B. Ulmer, V. Van Grootel, R. Vanderspek, J. Venturini, N. A. Walton, J. N. Winn, B. Wohler
Abstrakt: We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93⁺₋₀⁰₀₆⁰⁷ R and a period of 21.583298⁺₋₀⁰₀₀₀₀₅₅⁰⁰⁰⁰⁵² d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): University of Cambridge, Eidgenössische Technische Hochschule Zürich, Universität Bern, Massachusetts Institute of Technology, University of St. Andrews, Universität Genf, Stockholm University, Österreichische Akademie der Wissenschaften (ÖAW), Technical University of Denmark (DTU), National Aeronautics & Space Administration (NASA), Harvard-Smithsonian Center for Astrophysics, Università degli Studi di Torino, Slovak Academy of Sciences (SAS), Slovenian Academy of Sciences and Arts, Eötvös Loránd University Budapest, University of California, Berkeley, Universidade do Porto, Chalmers University of Technology, Stephen F. Austin State University, Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna, Universitat Autònoma de Barcelona , Spanish National Research Council (CSIC), Institut d'Estudis Espacials de Catalunya (IEEC), Admatis, European Space Astronomy Centre (ESA), Université Grenoble-Alpes, INAF - Osservatorio Astronomico di Padova, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Université de Paris, American Association of Variable Star Observers (AAVSO), INAF-Osservatorio Astrofisico di Torino, Lund University, Aix-Marseille Université, Université de Liège, University of New Mexico, Leiden University, University of California, Santa Cruz, European Space Research & Technology Centre (ESA/ESTEC), MTA Társadalomtudományi Kutatóközpont, Université de recherche Paris Sciences et Lettres, University of North Carolina at Chapel Hill, Université Paris VI - Pierre-et-Marie-Curie, European Southern Observatory (Germany), University of Chicago, Keele University, Proto-Logic LLC, University of Birmingham, INAF-Osservatorio Astrofisico di Catania, Università degli Studi di Padova, University of Warwick, Technische Universität Berlin, Freie Universität Berlin (FU), University of Maryland, College Park, Hazelwood Observatory, Princeton University, SETI Institute
Journal: Monthly Notices of the Royal Astronomical Society
Band: 523
Seiten: 3090-3118
Anzahl der Seiten: 29
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stad1369
Publikationsdatum: 08-2023
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/4dcee8a6-0039-4008-ab29-f84bbb88a105

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