Six transiting planets and a chain of Laplace resonances in TOI-178

A. Leleu; Y. Alibert; N. C. Hara; M. J. Hooton; T. G. Wilson; P. Robutel; J.-B. Delisle; J. Laskar; S. Hoyer; C. Lovis; E. M. Bryant; E. Ducrot; J. Cabrera; L. Delrez; J. S. Acton; V. Adibekyan; R. Allart; C. Allende Prieto; R. Alonso; D. Alves; D. R. Anderson; D. Angerhausen; G. Anglada Escudé; J. Asquier; D. Barrado; S. C. C. Barros; W. Baumjohann; D. Bayliss; M. Beck; T. Beck; A. Bekkelien; W. Benz; N. Billot; A. Bonfanti; X. Bonfils; F. Bouchy; V. Bourrier; G. Boué; A. Brandeker; C. Broeg; M. Buder; A. Burdanov; M. R. Burleigh; T. Bárczy; A. C. Cameron; S. Chamberlain; S. Charnoz; B. F. Cooke; C. Corral Van Damme; A. C. M. Correia; S. Cristiani; M. Damasso; M. B. Davies; M. Deleuil; O. D. S. Demangeon; B.-O. Demory; P. Di Marcantonio; G. Di Persio; X. Dumusque; D. Ehrenreich; A. Erikson; P. Figueira; A. Fortier; L. Fossati; M. Fridlund; D. Futyan; D. Gandolfi; A. García Muñoz; L. J. Garcia; S. Gill; E. Gillen; M. Gillon; M. R. Goad; J. I. González Hernández; M. Guedel; M. N. Günther; J. Haldemann; B. Henderson; K. Heng; A. E. Hogan; K. Isaak; E. Jehin; J. S. Jenkins; A. Jordán; L. Kiss; M. H. Kristiansen; K. Lam; B. Lavie; A. Lecavelier des Etangs; M. Lendl; J. Lillo-Box; G. Lo Curto; D. Magrin; C. J. A. P. Martins; P. F. L. Maxted; J. McCormac; A. Mehner; G. Micela; P. Molaro; M. Moyano; C. A. Murray; V. Nascimbeni; N. J. Nunes; G. Olofsson; H. P. Osborn; M. Oshagh; R. Ottensamer; I. Pagano; E. Pallé; P. P. Pedersen; F. A. Pepe; C. M. Persson; G. Peter; G. Piotto; G. Polenta; D. Pollacco; E. Poretti; F. J. Pozuelos; D. Queloz; R. Ragazzoni; N. Rando; F. Ratti; H. Rauer; L. Raynard; R. Rebolo; C. Reimers; I. Ribas; N. C. Santos; G. Scandariato; J. Schneider; D. Sebastian; M. Sestovic; A. E. Simon; A. M. S. Smith; S. G. Sousa; A. Sozzetti; M. Steller; A. Suárez Mascareño; Gy. M. Szabó; D. Ségransan; N. Thomas; S. Thompson; R. H. Tilbrook; A. Triaud; O. Turner; S. Udry; V. Van Grootel; H. Venus; F. Verrecchia; J. I. Vines; N. A. Walton; R. G. West; P. J. Wheatley; D. Wolter; M. R. Zapatero Osorio

doi:10.1051/0004-6361/202039767

Six transiting planets and a chain of Laplace resonances in TOI-178

A. Leleu, Y. Alibert, N. C. Hara, M. J. Hooton, T. G. Wilson, P. Robutel, J.-B. Delisle, J. Laskar, S. Hoyer, C. Lovis, E. M. Bryant, E. Ducrot, J. Cabrera, L. Delrez, J. S. Acton, V. Adibekyan, R. Allart, C. Allende Prieto, R. Alonso, D. AlvesD. R. Anderson, D. Angerhausen, G. Anglada Escudé, J. Asquier, D. Barrado, S. C. C. Barros, W. Baumjohann, D. Bayliss, M. Beck, T. Beck, A. Bekkelien, W. Benz, N. Billot, A. Bonfanti, X. Bonfils, F. Bouchy, V. Bourrier, G. Boué, A. Brandeker, C. Broeg, M. Buder, A. Burdanov, M. R. Burleigh, T. Bárczy, A. C. Cameron, S. Chamberlain, S. Charnoz, B. F. Cooke, C. Corral Van Damme, A. C. M. Correia, S. Cristiani, M. Damasso, M. B. Davies, M. Deleuil, O. D. S. Demangeon, B.-O. Demory, P. Di Marcantonio, G. Di Persio, X. Dumusque, D. Ehrenreich, A. Erikson, P. Figueira, A. Fortier, L. Fossati, M. Fridlund, D. Futyan, D. Gandolfi, A. García Muñoz, L. J. Garcia, S. Gill, E. Gillen, M. Gillon, M. R. Goad, J. I. González Hernández, M. Guedel, M. N. Günther, J. Haldemann, B. Henderson, K. Heng, A. E. Hogan, K. Isaak, E. Jehin, J. S. Jenkins, A. Jordán, L. Kiss, M. H. Kristiansen, K. Lam, B. Lavie, A. Lecavelier des Etangs, M. Lendl, J. Lillo-Box, G. Lo Curto, D. Magrin, C. J. A. P. Martins, P. F. L. Maxted, J. McCormac, A. Mehner, G. Micela, P. Molaro, M. Moyano, C. A. Murray, V. Nascimbeni, N. J. Nunes, G. Olofsson, H. P. Osborn, M. Oshagh, R. Ottensamer, I. Pagano, E. Pallé, P. P. Pedersen, F. A. Pepe, C. M. Persson, G. Peter, G. Piotto, G. Polenta, D. Pollacco, E. Poretti, F. J. Pozuelos, D. Queloz, R. Ragazzoni, N. Rando, F. Ratti, H. Rauer, L. Raynard, R. Rebolo, C. Reimers, I. Ribas, N. C. Santos, G. Scandariato, J. Schneider, D. Sebastian, M. Sestovic, A. E. Simon, A. M. S. Smith, S. G. Sousa, A. Sozzetti, M. Steller, A. Suárez Mascareño, Gy. M. Szabó, D. Ségransan, N. Thomas, S. Thompson, R. H. Tilbrook, A. Triaud, O. Turner, S. Udry, V. Van Grootel, H. Venus, F. Verrecchia, J. I. Vines, N. A. Walton, R. G. West, P. J. Wheatley, D. Wolter, M. R. Zapatero Osorio

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Abstract

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152_−0.070^+0.073 to 2.87_−0.13^+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02_−0.23^+0.28 to 0.177_−0.061^+0.055 times the Earth’s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

Original language	English
Article number	A26
Journal	Astronomy and Astrophysics
Volume	649
Number of pages	29
ISSN	0004-6361
DOIs	https://doi.org/10.1051/0004-6361/202039767
Publication status	Published - 2021

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Leleu, A., Alibert, Y., Hara, N. C., Hooton, M. J., Wilson, T. G., Robutel, P., Delisle, J.-B., Laskar, J., Hoyer, S., Lovis, C., Bryant, E. M., Ducrot, E., Cabrera, J., Delrez, L., Acton, J. S., Adibekyan, V., Allart, R., Allende Prieto, C., Alonso, R., ... Zapatero Osorio, M. R. (2021). Six transiting planets and a chain of Laplace resonances in TOI-178. Astronomy and Astrophysics, 649, Article A26. https://doi.org/10.1051/0004-6361/202039767

@article{01f046b5034942d1b5620d0e4e49e4e4,

title = "Six transiting planets and a chain of Laplace resonances in TOI-178",

abstract = "Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152−0.070+0.073 to 2.87−0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02−0.23+0.28 to 0.177−0.061+0.055 times the Earth{\textquoteright}s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.",

author = "A. Leleu and Y. Alibert and Hara, {N. C.} and Hooton, {M. J.} and Wilson, {T. G.} and P. Robutel and J.-B. Delisle and J. Laskar and S. Hoyer and C. Lovis and Bryant, {E. M.} and E. Ducrot and J. Cabrera and L. Delrez and Acton, {J. S.} and V. Adibekyan and R. Allart and {Allende Prieto}, C. and R. Alonso and D. Alves and Anderson, {D. R.} and D. Angerhausen and {Anglada Escud{\'e}}, G. and J. Asquier and D. Barrado and Barros, {S. C. C.} and W. Baumjohann and D. Bayliss and M. Beck and T. Beck and A. Bekkelien and W. Benz and N. Billot and A. Bonfanti and X. Bonfils and F. Bouchy and V. Bourrier and G. Bou{\'e} and A. Brandeker and C. Broeg and M. Buder and A. Burdanov and Burleigh, {M. R.} and T. B{\'a}rczy and Cameron, {A. C.} and S. Chamberlain and S. Charnoz and Cooke, {B. F.} and {Corral Van Damme}, C. and Correia, {A. C. M.} and S. Cristiani and M. Damasso and Davies, {M. B.} and M. Deleuil and Demangeon, {O. D. S.} and B.-O. Demory and {Di Marcantonio}, P. and {Di Persio}, G. and X. Dumusque and D. Ehrenreich and A. Erikson and P. Figueira and A. Fortier and L. Fossati and M. Fridlund and D. Futyan and D. Gandolfi and {Garc{\'i}a Mu{\~n}oz}, A. and Garcia, {L. J.} and S. Gill and E. Gillen and M. Gillon and Goad, {M. R.} and {Gonz{\'a}lez Hern{\'a}ndez}, {J. I.} and M. Guedel and G{\"u}nther, {M. N.} and J. Haldemann and B. Henderson and K. Heng and Hogan, {A. E.} and K. Isaak and E. Jehin and Jenkins, {J. S.} and A. Jord{\'a}n and L. Kiss and Kristiansen, {M. H.} and K. Lam and B. Lavie and {Lecavelier des Etangs}, A. and M. Lendl and J. Lillo-Box and {Lo Curto}, G. and D. Magrin and Martins, {C. J. A. P.} and Maxted, {P. F. L.} and J. McCormac and A. Mehner and G. Micela and P. Molaro and M. Moyano and Murray, {C. A.} and V. Nascimbeni and Nunes, {N. J.} and G. Olofsson and Osborn, {H. P.} and M. Oshagh and R. Ottensamer and I. Pagano and E. Pall{\'e} and Pedersen, {P. P.} and Pepe, {F. A.} and Persson, {C. M.} and G. Peter and G. Piotto and G. Polenta and D. Pollacco and E. Poretti and Pozuelos, {F. J.} and D. Queloz and R. Ragazzoni and N. Rando and F. Ratti and H. Rauer and L. Raynard and R. Rebolo and C. Reimers and I. Ribas and Santos, {N. C.} and G. Scandariato and J. Schneider and D. Sebastian and M. Sestovic and Simon, {A. E.} and Smith, {A. M. S.} and Sousa, {S. G.} and A. Sozzetti and M. Steller and {Su{\'a}rez Mascare{\~n}o}, A. and Szab{\'o}, {Gy. M.} and D. S{\'e}gransan and N. Thomas and S. Thompson and Tilbrook, {R. H.} and A. Triaud and O. Turner and S. Udry and {Van Grootel}, V. and H. Venus and F. Verrecchia and Vines, {J. I.} and Walton, {N. A.} and West, {R. G.} and Wheatley, {P. J.} and D. Wolter and {Zapatero Osorio}, {M. R.}",

year = "2021",

doi = "10.1051/0004-6361/202039767",

language = "English",

volume = "649",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

}

Leleu, A, Alibert, Y, Hara, NC, Hooton, MJ, Wilson, TG, Robutel, P, Delisle, J-B, Laskar, J, Hoyer, S, Lovis, C, Bryant, EM, Ducrot, E, Cabrera, J, Delrez, L, Acton, JS, Adibekyan, V, Allart, R, Allende Prieto, C, Alonso, R, Alves, D, Anderson, DR, Angerhausen, D, Anglada Escudé, G, Asquier, J, Barrado, D, Barros, SCC, Baumjohann, W, Bayliss, D, Beck, M, Beck, T, Bekkelien, A, Benz, W, Billot, N, Bonfanti, A, Bonfils, X, Bouchy, F, Bourrier, V, Boué, G, Brandeker, A, Broeg, C, Buder, M, Burdanov, A, Burleigh, MR, Bárczy, T, Cameron, AC, Chamberlain, S, Charnoz, S, Cooke, BF, Corral Van Damme, C, Correia, ACM, Cristiani, S, Damasso, M, Davies, MB, Deleuil, M, Demangeon, ODS, Demory, B-O, Di Marcantonio, P, Di Persio, G, Dumusque, X, Ehrenreich, D, Erikson, A, Figueira, P, Fortier, A, Fossati, L, Fridlund, M, Futyan, D, Gandolfi, D, García Muñoz, A, Garcia, LJ, Gill, S, Gillen, E, Gillon, M, Goad, MR, González Hernández, JI, Guedel, M, Günther, MN, Haldemann, J, Henderson, B, Heng, K, Hogan, AE, Isaak, K, Jehin, E, Jenkins, JS, Jordán, A, Kiss, L, Kristiansen, MH, Lam, K, Lavie, B, Lecavelier des Etangs, A, Lendl, M, Lillo-Box, J, Lo Curto, G, Magrin, D, Martins, CJAP, Maxted, PFL, McCormac, J, Mehner, A, Micela, G, Molaro, P, Moyano, M, Murray, CA, Nascimbeni, V, Nunes, NJ, Olofsson, G, Osborn, HP, Oshagh, M, Ottensamer, R, Pagano, I, Pallé, E, Pedersen, PP, Pepe, FA, Persson, CM, Peter, G, Piotto, G, Polenta, G, Pollacco, D, Poretti, E, Pozuelos, FJ, Queloz, D, Ragazzoni, R, Rando, N, Ratti, F, Rauer, H, Raynard, L, Rebolo, R, Reimers, C, Ribas, I, Santos, NC, Scandariato, G, Schneider, J, Sebastian, D, Sestovic, M, Simon, AE, Smith, AMS, Sousa, SG, Sozzetti, A, Steller, M, Suárez Mascareño, A, Szabó, GM, Ségransan, D, Thomas, N, Thompson, S, Tilbrook, RH, Triaud, A, Turner, O, Udry, S, Van Grootel, V, Venus, H, Verrecchia, F, Vines, JI, Walton, NA, West, RG, Wheatley, PJ, Wolter, D & Zapatero Osorio, MR 2021, 'Six transiting planets and a chain of Laplace resonances in TOI-178', Astronomy and Astrophysics, vol. 649, A26. https://doi.org/10.1051/0004-6361/202039767

TY - JOUR

T1 - Six transiting planets and a chain of Laplace resonances in TOI-178

AU - Leleu, A.

AU - Alibert, Y.

AU - Hara, N. C.

AU - Hooton, M. J.

AU - Wilson, T. G.

AU - Robutel, P.

AU - Delisle, J.-B.

AU - Laskar, J.

AU - Hoyer, S.

AU - Lovis, C.

AU - Bryant, E. M.

AU - Ducrot, E.

AU - Cabrera, J.

AU - Delrez, L.

AU - Acton, J. S.

AU - Adibekyan, V.

AU - Allart, R.

AU - Allende Prieto, C.

AU - Alonso, R.

AU - Alves, D.

AU - Anderson, D. R.

AU - Angerhausen, D.

AU - Anglada Escudé, G.

AU - Asquier, J.

AU - Barrado, D.

AU - Barros, S. C. C.

AU - Baumjohann, W.

AU - Bayliss, D.

AU - Beck, M.

AU - Beck, T.

AU - Bekkelien, A.

AU - Benz, W.

AU - Billot, N.

AU - Bonfanti, A.

AU - Bonfils, X.

AU - Bouchy, F.

AU - Bourrier, V.

AU - Boué, G.

AU - Brandeker, A.

AU - Broeg, C.

AU - Buder, M.

AU - Burdanov, A.

AU - Burleigh, M. R.

AU - Bárczy, T.

AU - Cameron, A. C.

AU - Chamberlain, S.

AU - Charnoz, S.

AU - Cooke, B. F.

AU - Corral Van Damme, C.

AU - Correia, A. C. M.

AU - Cristiani, S.

AU - Damasso, M.

AU - Davies, M. B.

AU - Deleuil, M.

AU - Demangeon, O. D. S.

AU - Demory, B.-O.

AU - Di Marcantonio, P.

AU - Di Persio, G.

AU - Dumusque, X.

AU - Ehrenreich, D.

AU - Erikson, A.

AU - Figueira, P.

AU - Fortier, A.

AU - Fossati, L.

AU - Fridlund, M.

AU - Futyan, D.

AU - Gandolfi, D.

AU - García Muñoz, A.

AU - Garcia, L. J.

AU - Gill, S.

AU - Gillen, E.

AU - Gillon, M.

AU - Goad, M. R.

AU - González Hernández, J. I.

AU - Guedel, M.

AU - Günther, M. N.

AU - Haldemann, J.

AU - Henderson, B.

AU - Heng, K.

AU - Hogan, A. E.

AU - Isaak, K.

AU - Jehin, E.

AU - Jenkins, J. S.

AU - Jordán, A.

AU - Kiss, L.

AU - Kristiansen, M. H.

AU - Lam, K.

AU - Lavie, B.

AU - Lecavelier des Etangs, A.

AU - Lendl, M.

AU - Lillo-Box, J.

AU - Lo Curto, G.

AU - Magrin, D.

AU - Martins, C. J. A. P.

AU - Maxted, P. F. L.

AU - McCormac, J.

AU - Mehner, A.

AU - Micela, G.

AU - Molaro, P.

AU - Moyano, M.

AU - Murray, C. A.

AU - Nascimbeni, V.

AU - Nunes, N. J.

AU - Olofsson, G.

AU - Osborn, H. P.

AU - Oshagh, M.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Pallé, E.

AU - Pedersen, P. P.

AU - Pepe, F. A.

AU - Persson, C. M.

AU - Peter, G.

AU - Piotto, G.

AU - Polenta, G.

AU - Pollacco, D.

AU - Poretti, E.

AU - Pozuelos, F. J.

AU - Queloz, D.

AU - Ragazzoni, R.

AU - Rando, N.

AU - Ratti, F.

AU - Rauer, H.

AU - Raynard, L.

AU - Rebolo, R.

AU - Reimers, C.

AU - Ribas, I.

AU - Santos, N. C.

AU - Scandariato, G.

AU - Schneider, J.

AU - Sebastian, D.

AU - Sestovic, M.

AU - Simon, A. E.

AU - Smith, A. M. S.

AU - Sousa, S. G.

AU - Sozzetti, A.

AU - Steller, M.

AU - Suárez Mascareño, A.

AU - Szabó, Gy. M.

AU - Ségransan, D.

AU - Thomas, N.

AU - Thompson, S.

AU - Tilbrook, R. H.

AU - Triaud, A.

AU - Turner, O.

AU - Udry, S.

AU - Van Grootel, V.

AU - Venus, H.

AU - Verrecchia, F.

AU - Vines, J. I.

AU - Walton, N. A.

AU - West, R. G.

AU - Wheatley, P. J.

AU - Wolter, D.

AU - Zapatero Osorio, M. R.

PY - 2021

Y1 - 2021

N2 - Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152−0.070+0.073 to 2.87−0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02−0.23+0.28 to 0.177−0.061+0.055 times the Earth’s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

AB - Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152−0.070+0.073 to 2.87−0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02−0.23+0.28 to 0.177−0.061+0.055 times the Earth’s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

U2 - 10.1051/0004-6361/202039767

DO - 10.1051/0004-6361/202039767

M3 - Journal article

SN - 0004-6361

VL - 649

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A26

ER -

Six transiting planets and a chain of Laplace resonances in TOI-178

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