1. TESS and CHEOPS Discover Two Warm Sub-Neptunes Transiting the Bright K-dwarf HD 15906
- Author
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Tuson, A., Queloz, D., Osborn, H. P., Wilson, T. G., Hooton, M. J., Beck, M., Lendl, M., Olofsson, G., Fortier, A., Bonfanti, A., Brandeker, A., Buchhave, L. A., Collier Cameron, A., Ciardi, D. R., Collins, K. A., Gandolfi, D., Garai, Z., Giacalone, S., Gomes da Silva, J., Howell, S. B., Patel, J. A., Persson, C. M., Serrano, L. M., Sousa, S. G., Ulmer-Moll, S., Vanderburg, A., Ziegler, C., Alibert, Y., Alonso, R., Anglada, G., Bàrczy, T., Barrado Navascues, D., Barros, S. C. C., Baumjohann, W., Beck, T., Benz, W., Billot, N., Bonfils, X., Borsato, L., Broeg, C., Cabrera, J., Charnoz, S., Conti, D. M., Csizmadia, Szilard, Cubillos, P. E., Davies, M. B., Deleuil, M., Delrez, L., Demangeon, O. D. S., Demory, B. -O., Dragomir, D., Dressing, C. D., Ehrenreich, D., Erikson, A., Essack, Z., Farinato, J., Fossati, L., Fridlund, M., Furlan, E., Gill, H., Gillon, M., Gnilka, C. L., Gonzales, E.J., Güdel, M., Günther, M. N., Hoyer, S., Isaak, K. G., Jenkins, J. M., Kiss, L. L., Laskar, J., Latham, D. W., Law, N., Lecavelier des Etangs, A., Curto, G. Lo, Lovis, C., Luque, R., Magrin, D., Mann, A. W., Maxted, P. F. L., Mayor, M., McDermott, S., Mecina, M., Mordasini, C., Mortier, A., Nascimbeni, V., Ottensamer, R., Pagano, I., Palle, E., Peter, G., Piotto, G., Pollacco, D., Pritchard, T., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H, Ribas, I., Ricker, G. R., Rieder, M., Santos, N. C., Savel, A. B., Scandariato, G., Schwarz, R. P., Seager, S., Ségransan, D., Shporer, A., Simon, A. E., Smith, A. M. S., Steller, M., Stockdale, C., Szabó, Gy. M., Thomas, N., Torres, G., Tronsgaard, R., Udry, S., Ulmer, B., Van Grootel, V., Vanderspek, R., Venturini, J., Walton, N. A., Winn, J. N., Wohler, B., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), and Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,planets and satellites: detection ,fundamental parameters [Planets and satellites] ,photometric [Techniques] ,TIC 4646810) ,individual: HD 15906 (TOI 461, TIC 4646810) [Stars] ,FOS: Physical sciences ,fundamental parameters [Stars] ,detection [Planets and satellites] ,techniques: photometric ,[SDU]Sciences of the Universe [physics] ,stars: fundamental parameters ,stars: individual: HD 15906 (TOI 461 ,planets and satellites: fundamental parameters ,Astrophysics - Earth and Planetary Astrophysics - Abstract
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 $\sim$ 734 days, 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 $\pm$ 0.08 R$_\oplus$ and a period of 10.924709 $\pm$ 0.000032 days, whilst HD 15906 c has a radius of 2.93$^{+0.07}_{-0.06}$ R$_\oplus$ and a period of 21.583298$^{+0.000052}_{-0.000055}$ days. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 $\pm$ 13 K and 532 $\pm$ 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm ($\lesssim$ 700 K) sub-Neptune sized planets transiting a bright star (G $\leq$ 10 mag). It is an excellent target for detailed characterisation studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution., 30 pages, 20 figures, 11 tables (including appendix). Published in MNRAS
- Published
- 2023
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