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A pair of sub-Neptunes transiting the bright K-dwarf TOI-1064 characterized with CHEOPS

2022; Oxford University Press; Volume: 511; Issue: 1 Linguagem: Inglês

10.1093/mnras/stab3799

1365-2966

T. G. Wilson, Elisa Goffo, Y. Alibert, D. Gandolfi, A. Bonfanti, C. M. Persson, A. Collier Cameron, M. Fridlund, L. Fossati, J. Korth, W. Benz, A. Deline, H.-G. Florén, P. Guterman, V. Adibekyan, M. J. Hooton, S. Hoyer, A. Leleu, Alexander J. Mustill, Sébastien Salmon, S. G. Sousa, Olga Suárez, Lyu Abe, A. Agabi, R. Alonso, G. Anglada‐Escudé, J. Asquier, T. Bárczy, D. Barrado, S. C. C. Barros, W. Baumjohann, Mathias Beck, T. Beck, N. Billot, X. Bonfıls, A. Brandeker, C. Broeg, Edward M. Bryant, M. R. Burleigh, Marco Buttu, J. Cabrera, S. Charnoz, David R. Ciardi, Ryan Cloutier, William D. Cochran, Karen A. Collins, Knicole D. Colón, Nicolas Crouzet, Szilárd Csizmadia, M. B. Davies, M. Deleuil, L. Delrez, O. D. S. Demangeon, Brice-Olivier Demory, Diana Dragomir, Georgina Dransfield, D. Ehrenreich, A. Erikson, A. Fortier, Tianjun Gan, Samuel Gill, M. Gillon, Crystal L. Gnilka, Nolan Grieves, S. Grziwa, M. Güdel, T. Guillot, Jonas Haldemann, Kevin Heng, K. Horne, Steve B. Howell, K. Isaak, Jon M. Jenkins, Eric L. N. Jensen, L. L. Kiss, G. Lacedelli, K. W. F. Lam, J. Laskar, David W. Latham, A. Lecavelier des Étangs, M. Lendl, Kathryn V. Lester, Alan M. Levine, John H. Livingston, C. Lovis, R. Luque, Demetrio Magrin, Wenceslas Marie-Sainte, P. F. L. Maxted, Andrew W. Mayo, B. McLean, M. Mečina, D. Mékarnia, V. Nascimbeni, Louise D. Nielsen, G. Olofsson, H. P. Osborn, H. L. M. Osborne, R. Ottensamer, I. Pagano, Ε. Πάλλη, G. Peter, G. Piotto, D. Pollacco, D. Queloz, Roberto Ragazzoni, N. Rando, H. Rauer, Seth Redfield, I. Ribas, G. Ricker, Martin Rieder, N. C. Santos, G. Scandariato, F. X. Schmider, Richard P. Schwarz, Nicholas J. Scott, Sara Seager, D. Ségransan, L. M. Serrano, A. E. Simon, A. M. S. Smith, M. Steller, Chris Stockdale, Gyula M. Szabó, N. Thomas, Eric B. Ting, A. H. M. J. Triaud, S. Udry, Vincent Van Eylen, V. Van Grootel, R. Vanderspek, Valentina Viotto, N. A. Walton, Joshua N. Winn,

Astrophysics and Star Formation Studies

We report the discovery and characterisation of a pair of sub-Neptunes transiting the bright K-dwarf TOI-1064 (TIC 79748331), initially detected in TESS photometry. To characterise the system, we performed and retrieved CHEOPS, TESS, and ground-based photometry, HARPS high-resolution spectroscopy, and Gemini speckle imaging. We characterise the host star and determine $T_{\rm eff, \star}=4734\pm67$ K, $R_{\star}=0.726\pm0.007$ $R_{\odot}$, and $M_{\star}=0.748\pm0.032$ $M_{\odot}$. We present a novel detrending method based on PSF shape-change modelling and demonstrate its suitability to correct flux variations in CHEOPS data. We confirm the planetary nature of both bodies and find that TOI-1064 b has an orbital period of $P_{\rm b}=6.44387\pm0.00003$ d, a radius of $R_{\rm b}=2.59\pm0.04$ $R_{\oplus}$, and a mass of $M_{\rm b}=13.5_{-1.8}^{+1.7}$ $M_{\oplus}$, whilst TOI-1064 c has an orbital period of $P_{\rm c}=12.22657^{+0.00005}_{-0.00004}$ d, a radius of $R_{\rm c}=2.65\pm0.04$ $R_{\oplus}$, and a 3$\sigma$ upper mass limit of 8.5 ${\rm M_{\oplus}}$. From the high-precision photometry we obtain radius uncertainties of $\sim$1.6%, allowing us to conduct internal structure and atmospheric escape modelling. TOI-1064 b is one of the densest, well-characterised sub-Neptunes, with a tenuous atmosphere that can be explained by the loss of a primordial envelope following migration through the protoplanetary disc. It is likely that TOI-1064 c has an extended atmosphere due to the tentative low density, however further RVs are needed to confirm this scenario and the similar radii, different masses nature of this system. The high-precision data and modelling of TOI-1064 b are important for planets in this region of mass-radius space, and it allows us to identify a trend in bulk density-stellar metallicity for massive sub-Neptunes that may hint at the formation of this population of planets.