AQUA: a collection of H<sub>2</sub>O equations of state for planetary models

Haldemann, Jonas; Alibert, Yann; Mordasini, Christoph; Benz, W.

doi:10.1051/0004-6361/202038367

Cited by 96 publications

(58 citation statements)

References 38 publications

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“…For the forward model, we assume that each planet is composed of four layers: an iron-sulfur inner core, a mantle, a water layer, and a gas layer. We used the equation of state (EOS) for Hakim et al (2018) for the core, the EOS from Sotin et al (2007) for the silicate mantle, and the EOS from Haldemann et al (2020) for the water. These three layers constitute the 'solid' part of the planets.…”

Section: Internal Structure Modellingmentioning

confidence: 99%

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

Leleu

Alibert²,

Hara³

et al. 2021

A&A

138

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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.

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Section: Internal Structure Modellingmentioning

confidence: 99%

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

Leleu

Alibert²,

Hara³

et al. 2021

A&A

138

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“…The problem with associating the second peak with water-rich planets is that it cannot explain why such planets do not fill the valley. Cores containing 50% rock-50% ice by mass would fall in the radius valley if they had a mass of ∼3-6 M ⊕ (Sotin et al 2007;Zeng et al 2019;Haldemann et al 2020;Owen & Wu 2017;Gupta & Schlichting 2019). Zeng et al (2019) showed that the Kepler size distribution can be matched if the icy planets are assumed to follow the mass distribution suggested by RV measurements, which encompasses masses in the range ∼6-15 M ⊕ , with a peak at ∼9 M ⊕ .…”

Section: Introductionmentioning

confidence: 99%

The nature of the radius valley

Venturini

Guilera

Haldemann

et al. 2020

A&A

Self Cite

151

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The existence of a radius valley in the Kepler size distribution stands as one of the most important observational constraints to understand the origin and composition of exoplanets with radii between those of Earth and Neptune. In this work we provide insights into the existence of the radius valley, first from a pure formation point of view and then from a combined formation-evolution model. We run global planet formation simulations including the evolution of dust by coagulation, drift, and fragmentation, and the evolution of the gaseous disc by viscous accretion and photoevaporation. A planet grows from a moon-mass embryo by either silicate or icy pebble accretion, depending on its position with respect to the water ice line. We include gas accretion, type I–II migration, and photoevaporation driven mass-loss after formation. We perform an extensive parameter study evaluating a wide range of disc properties and initial locations of the embryo. We find that due to the change in dust properties at the water ice line, rocky cores form typically with ∼3 M⊕ and have a maximum mass of ∼5 M⊕, while icy cores peak at ∼10 M⊕, with masses lower than 5 M⊕ being scarce. When neglecting the gaseous envelope, the formed rocky and icy cores account naturally for the two peaks of the Kepler size distribution. The presence of massive envelopes yields planets more massive than ∼10 M⊕ with radii above 4 R⊕. While the first peak of the Kepler size distribution is undoubtedly populated by bare rocky cores, as shown extensively in the past, the second peak can host half-rock–half-water planets with thin or non-existent H-He atmospheres, as suggested by a few previous studies. Some additional mechanisms inhibiting gas accretion or promoting envelope mass-loss should operate at short orbital periods to explain the presence of ∼10–40 M⊕ planets falling in the second peak of the size distribution.

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“…It should be noted that the position of the water line in the diagram is very sensitive to used EOS (e.g. Haldemann et al 2020). Fig.…”

Section: Parametermentioning

confidence: 99%

TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet

Osborn

Armstrong

Cale

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the bright (Vmag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 ± 0.7 d using archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431 b is a super-Earth with a period of 0.49 d, a radius of 1.28 ± 0.04 R⊕, a mass of 3.07 ± 0.35 M⊕, and a density of 8.0 ± 1.0 g cm−3; TOI-431 d is a sub-Neptune with a period of 12.46 d, a radius of 3.29 ± 0.09 R⊕, a mass of $9.90^{+1.53}_{-1.49}$ M⊕, and a density of 1.36 ± 0.25 g cm−3. We find a third planet, TOI-431 c, in the High Accuracy Radial velocity Planet Searcher RV data, but it is not seen to transit in the TESS light curves. It has an Msin i of $2.83^{+0.41}_{-0.34}$ M⊕, and a period of 4.85 d. TOI-431 d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431 b may be a stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431 b is a prime TESS discovery for the study of rocky planet phase curves.

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AQUA: a collection of H₂O equations of state for planetary models

Cited by 96 publications

References 38 publications

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

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

The nature of the radius valley

TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet

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AQUA: a collection of H2O equations of state for planetary models

Cited by 96 publications

References 38 publications

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

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

The nature of the radius valley

TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet

Contact Info

Product

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AQUA: a collection of H₂O equations of state for planetary models