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

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.; Prieto, C. Allende; Alonso, R.; Alves, D.; Anderson, D. R.; Angerhausen, D.; Escudé, G. Anglada; Asquier, J.; Barrado, D.; Barros, S. C. C.; 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, M. R.; Bárczy, T.; Cameron, A. C.; Chamberlain, S.; Charnoz, S.; Cooke, B. F.; Van Damme, C. Corral; Correia, A. C. M.; Cristiani, S.; Damasso, M.; Davies, M. B.; Deleuil, M.; Demangeon, O. D. S.; 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.; Muñoz, A. García; Garcia, L. J.; Gill, S.; Gillen, E.; Gillon, M.; Goad, M. R.; Hernández, J. I. González; Guedel, M.; Günther, M. N.; Haldemann, J.; Henderson, B.; Heng, K.; Hogan, A. E.; Isaak, K.; Jehin, E.; Jenkins, J. S.; Jordán, A.; Kiss, L.; Kristiansen, M. H.; Lam, K.; Lavie, B.; Etangs, A. Lecavelier des; Lendl, M.; Lillo-Box, J.; Curto, G. Lo; Magrin, D.; Martins, C. J. A. P.; Maxted, P. F. L.; McCormac, J.; Mehner, A.; Micela, G.; Molaro, P.; Moyano, M.; Murray, C. A.; Nascimbeni, V.; Nunes, N. J.; Olofsson, G.; Osborn, H. P.; Oshagh, M.; Ottensamer, R.; Pagano, I.; Pallé, E.; Pedersen, P. P.; Pepe, F. A.; Persson, C. M.; Peter, G.; Piotto, G.; Polenta, G.; Pollacco, D.; Poretti, E.; Pozuelos, F. J.; Queloz, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Raynard, L.; Rebolo, R.; Reimers, C.; Ribas, I.; Santos, N. C.; Scandariato, G.; Schneider, J.; Sebastian, D.; Sestovic, M.; Simon, A. E.; Smith, A. M. S.; Sousa, S. G.; Sozzetti, A.; Steller, M.; Mascareño, A. Suárez; Szabó, Gy. M.; Ségransan, D.; Thomas, N.; Thompson, S.; Tilbrook, R. H.; Triaud, A.; Turner, O.; Udry, S.; Van Grootel, V.; Venus, H.; Verrecchia, F.; Vines, J. I.; Walton, N. A.; West, R. G.; Wheatley, P. J.; Wolter, D.; Osorio, M. R. Zapatero

doi:10.48550/arxiv.2101.09260

Cited by 11 publications

(17 citation statements)

References 38 publications

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“…Approaches as implemented in this study can be applied to other systems. Recently, Leleu et al (2021) complete the planet discovery in TOI-178 system and found that all six planets except the innermost one form a 2:4:6:9:12 chain of Laplace resonances. The period ratio of the second innermost planet over the innermost one is ∼1.69.…”

Section: Discussionmentioning

confidence: 99%

“…At the same time, Mah (2018) and Brasser et al (2019) find that the libration centre of the 3BR angles may jump to different values after tens of thousand years. Until now, only several planetary systems are known to harbour 3BRs: GJ 876 (Rivera et al 2010), Kepler-60 (Goździewski et al 2016), Kepler-80 (Xie 2013;MacDonald et al 2016MacDonald et al , 2021, Kepler-223 (Mills et al 2016), K2-138 (Christiansen et al 2018;Lopez et al 2019), HD-158259 (Hara et al 2020), and TOI-178 (Leleu et al 2021). Recently, one 3BR is confirmed in Kepler-221 (Goldberg & Batygin 2021) seven years after its discovery (Rowe et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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The dynamics of the TRAPPIST-1 system in the context of its formation

Huang,

Ormel

2021

Preprint

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TRAPPIST-1 is an 0.09 𝑀 star, which harbours a system of seven Earth-sized planets. Two main features stand out: (i) all planets have similar radii, masses, and compositions; and (ii) all planets are in resonance. Previous works have outlined a pebble-driven formation scenario where planets of similar composition form sequentially at the H 2 O snowline (∼0.1 au for this low-mass star). It was hypothesized that the subsequent formation and migration led to the current resonant configuration. Here, we investigate whether the sequential planet formation model is indeed capable to produce the present-day resonant configuration, characterized by its two-body and three-body mean motion resonances structure. We carry out N-body simulations, accounting for type-I migration, stellar tidal damping, disc eccentricity damping, and featuring a migration barrier located at the disc's inner edge. We demonstrate that the present-day dynamical configuration of the TRAPPIST-1 system is in line with the sequential formation/migration model. First, a chain of first-order resonances was formed at the disc inner edge by convergent migration. We argue that TRAPPIST-1b and c marched across the migration barrier, into the gas-free cavity, during the dispersal of the gas disc. The dispersing disc then pushed planets b and c inward until they settled in a configuration close to the observed resonances. Thereafter, the stellar tidal torque also attributed towards a modest separation of the inner system. We argue that our scenario is also applicable to other compact resonant planet systems.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The dynamics of the TRAPPIST-1 system in the context of its formation

Huang,

Ormel

2021

Preprint

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“…On the other hand, near 2:1 period-ratio planetary pairs in FGK systems tend to have an additional planet at an outer orbit rather than inner one as shown in the bottom panels of Figure 19. Note that the TOI-178 system is an exception to this trend, i.e., the near 2:1 period ratio pair of TOI-178c and d has an additional inner planet (TOI-178b) despite that the host star is a K dwarf; however, the host star has an effective temperature of T eff = 4316K (Leleu et al 2021), which is close to the temperature range of M dwarfs < 4000K.…”

Section: Period Ratio Of Toi-1749c and Dmentioning

confidence: 97%

TOI-1749: an M dwarf with a Trio of Planets including a Near-Resonant Pair

Fukui,

Korth,

Livingston

et al. 2021

Preprint

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We report the discovery of one super-Earth-(TOI-1749b) and two sub-Neptune-sized planets (TOI-1749c and TOI-1749d) transiting an early M dwarf at a distance of 100 pc, which were first identified as planetary candidates using data from the TESS photometric survey. We have followed up this system from the ground by means of multiband transit photometry, adaptive-optics imaging, and lowresolution spectroscopy, from which we have validated the planetary nature of the candidates. We find that TOI-1749b, c, and d have orbital periods of 2.39, 4.49, and 9.05 days, and radii of 1.4, 2.1, and 2.5 R ⊕ , respectively. We also place 95% confidence upper limits on the masses of 57, 14, and 15 M ⊕ for TOI-1749b, c, and d, respectively, from transit timing variations. The periods, sizes, and tentative masses of these planets are in line with a scenario in which all three planets initially had a hydrogen envelope on top of a rocky core, and only the envelope of the innermost planet has been stripped away by photoevaporation and/or core-powered mass loss mechanisms. These planets are similar to other planetary trios found around M dwarfs, such as c,c,d, in the sense that the outer pair has a period ratio within 1% of 2. Such a characteristic orbital configuration, in which an additional planet is located interior to a near 2:1 period-ratio pair, is relatively rare around FGK dwarfs.

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“…With planets c and d very near MMR, it is noticeable that there are not more pairs of planets also spaced in near resonant orbits. Following the peas-in-a-pod architecture where multi-planet systems show similarly sized planets in regular orbital distance spacing, we might expect more than just one pair in this system to exhibit near-resonance, especially considering that the transiting planets have very similar radii (Leleu et al 2021).…”

Section: Gap Complexitymentioning

confidence: 97%

TESS-Keck Survey IX: Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian Plus a Distant Sub-Stellar Companion

Lubin,

Van Zandt,

Holcomb

et al. 2021

Preprint

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Exoplanet systems with multiple transiting planets are natural laboratories for testing planetary astrophysics. One such system is HD 191939 (TOI-1339), a bright (V=9) and Sun-like (G9V) star, which TESS found to host three transiting planets (b, c, and d). The planets have periods of 9, 29, and 38 days each with similar sizes from 3 to 3.4 R ⊕ . To further characterize the system, we measured the radial velocity (RV) of HD 191939 over 415 days with Keck/HIRES and APF/Levy. We find that M b = 10.4 ± 0.9M ⊕ and M c = 7.2 ± 1.4M ⊕ , which are low compared to most known planets of comparable radii. The RVs yield only an upper-limit on M d (<5.8 M ⊕ at 2σ). The RVs further reveal a fourth planet (e) with a minimum mass of 0.34 ± 0.01 M Jup and an orbital period of 101.4 ± 0.4 days. Despite its non-transiting geometry, secular interactions between planet e and the inner transiting planets indicate that planet e is coplanar with the transiting planets (∆i < 10 • ). We identify a second non-transiting sub-stellar companion (f) with a mass of 8-59 M Jup and period of 9-46 years based on a joint analysis of RVs and astrometry from Gaia and Hipparcos. As a bright star hosting multiple planets with well-measured masses, HD 191939 presents many options for comparative planetary astronomy including characterization with JWST.

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

Cited by 11 publications

References 38 publications

The dynamics of the TRAPPIST-1 system in the context of its formation

The dynamics of the TRAPPIST-1 system in the context of its formation

TOI-1749: an M dwarf with a Trio of Planets including a Near-Resonant Pair

TESS-Keck Survey IX: Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian Plus a Distant Sub-Stellar Companion

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