Lava worlds: From early earth to exoplanets

Chao, Keng‐Hsien; deGraffenried, R.; Lach, Mackenzie; Nelson, William Stuart; Truax, Kelly; Gaidos, Eric

doi:10.1016/j.chemer.2020.125735

Cited by 33 publications

(18 citation statements)

References 400 publications

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“…The youth of TOI-1807b makes it an even more compelling target for secondary eclipse spectroscopy, as the luminosity of the planet's cooling core may be an order of magnitude higher than it would be at older (>1 Gyr) ages (Linder et al 2019). Finally, as a candidate "lava world" (Chao et al 2020), TOI-1807b presents an opportunity to study the early evolution of these poorly understood objects.…”

Section: Discussionmentioning

confidence: 99%

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

Hedges

Hughes

Zhou

et al. 2021

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We report the discovery of two planetary systems around comoving stars: TOI-2076 (TIC 27491137) and TOI-1807 (TIC 180695581). TOI-2076 is a nearby (41.9 pc) multiplanetary system orbiting a young (204±50 Myr), bright (K=7.115 in TIC v8.1) start. TOI-1807 hosts a single transiting planet and is similarly nearby (42.58 pc), similarly young (180±40 Myr), and bright. Both targets exhibit significant, periodic variability due to starspots, characteristic of their young ages. Using photometric data collected by TESS we identify three transiting planets around TOI-2076 with radii of R b =3.3±0.04 R ⊕ , R c =4.4±0.05 R ⊕ , and R d =4.1±0.07 R ⊕ . Planet TOI-2076b has a period of P b =10.356 days. For both TOI-2076c and d, TESS observed only two transits, separated

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Section: Discussionmentioning

confidence: 99%

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

Hedges

Hughes

Zhou

et al. 2021

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“…Immediately after their formation, telluric planets very likely experience a short phase of complete melting owing to the heat released in their accretion and core formation processes (Jaupart et al 2007;Chao et al 2021). The duration of this phase is limited to ≈10 Myr for an Earth-mass planet because of the rapid cooling of the interior magma ocean (e.g., Abe 1997;Jaupart et al 2007).…”

Section: Discussionmentioning

confidence: 99%

An internal heating mechanism operating in ultra-short-period planets orbiting magnetically active stars

Lanza

2021

A&A

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Context. Rocky planets with orbital periods shorter than ~1 day have been discovered by the method of transits and their study can provide information on Earth-like planets not available from bodies on longer period orbits. Aims. A new mechanism for the internal heating of such ultra-short-period planets is proposed based on the gravitational perturbation produced by a non-axisymmetric quadrupole moment of their host stars. Such a quadrupole is due to the magnetic flux tubes in the stellar convection zone, unevenly distributed in longitude and persisting for many stellar rotations as observed in young late-type stars. Methods. The rotation period of the host star evolves from its shortest value on the zero-age main sequence (ZAMS) to longer periods due to the loss of angular momentum through a magnetized wind. If the stellar rotation period comes close to twice the orbital period of the planet, the quadrupole leads to a spin-orbit resonance that excites oscillations of the star-planet separation. As a consequence, a strong tidal dissipation is produced inside the planet that converts the energy of the oscillations into internal heat. The total heat released inside the planet scales as a−8, where a is the orbit semimajor axis, and it is largely independent of the details of the planetary internal dissipation or the lifetime of the stellar magnetic flux tubes. Results. We illustrate the operation of the mechanism by modeling the evolution of the stellar rotation and of the innermost planetary orbit under the action of the stellar wind and the tides in the cases of CoRoT-7, Kepler-78, and K2-141 whose present orbital periods range between 0.28 and 0.85 days. If the spin-orbit resonance occurs, the maximum power dissipated inside the planets ranges between 1018 and 1019 W, while the total dissipated energy is on the order of 1030−1032 J over a time interval as short as (1−4.5) × 104 yr. Conclusions. Our illustrative models suggest that, if their host stars started their evolution on the ZAMS as fast rotators with periods between 0.5 and 1.0 days, the resonance occurred after about 40 Myr since the host stars settled on the ZAMS in all the three cases. This huge heating over such a short time interval produces a complete melting of the planetary interiors and may shut off their hydromagnetic dynamos. These may initiate a successive phase of intense internal heating owing to unipolar magnetic star-planet interactions and affect the composition and the escape of their atmospheres, producing effects that could be observable during the entire lifetime of the planets.

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“…As with most short-period exoplanets, lava planets are expected to be tidally-locked into synchronous rotation (Léger et al 2011). For a review of lava planets, read Chao et al (2021).…”

Section: Introductionmentioning

confidence: 99%

Deep two-phase, hemispherical magma oceans on lava planets

Boukaré,

Cowan,

Badro

2022

Preprint

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Astronomers have discovered a handful of exoplanets with rocky bulk compositions but orbiting so close to their host star that the surface of the planet must be at least partially molten. It is expected that the dayside of such "lava planets" harbors a rock vapor atmosphere that flows quickly towards the airless nightside-this partial atmosphere is critical to the interpretation of lava planet observations, but transports negligible heat towards the nightside. As a result, the surface temperature of the magma ocean may range from 3000 K near the sub-stellar point down to 1500 K near the day-night terminator. We use simple models incorporating the thermodynamics and geochemistry of partial melt to predict the physical and chemical properties of the magma ocean as a function of the distance from the sub-stellar point. Our two principal findings are that 1) the dayside magma ocean is much deeper than previously thought, probably extending down to the core-mantle boundary in some locations, and 2) much of the dayside is only partially molten, leading to gradients in the surface chemistry of the magma ocean. These findings have important implications for the dynamics of the magma ocean as well as the composition and dynamics of the atmosphere.

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Lava worlds: From early earth to exoplanets

Cited by 33 publications

References 400 publications

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

An internal heating mechanism operating in ultra-short-period planets orbiting magnetically active stars

Deep two-phase, hemispherical magma oceans on lava planets

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