Thermal torque effects on the migration of growing low-mass planets

Guilera, O. M.; Cuello, Nicolás; Montesinos, Matías; Bertolami, M. M. Miller; Ronco, M. P.; Cuadra, Jorge; Masset, F.

doi:10.1093/mnras/stz1158

Cited by 42 publications

(48 citation statements)

References 83 publications

(208 reference statements)

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“…They noted that the effects of the heating force are expected to be significant for planet formation application, via, e.g., the Earth developing a non-negligible eccentricity and inclination with respect to the protoplanetary disc for realistic disc parameters. These conclusions and the analytic result (Equation 11) were confirmed with numerical simulations by Velasco Romero & Masset (2019), Chrenko & Lambrechts (2019) and Guilera et al (2019). In application to our particular problem, we note that the density in the central part of the protoplanet is initially homogeneous with a nearly constant ρ0 ≈ 10 −9 gcm −3 .…”

Section: Dynamics Of the Luminous Coresupporting

confidence: 86%

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores

Humphries

Nayakshin

2019

Monthly Notices of the Royal Astronomical Society

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Recent ALMA observations may indicate a surprising abundance of sub-Jovian planets on very wide orbits in protoplanetary discs that are only a few million years old. These planets are too young and distant to have been formed via the Core Accretion (CA) scenario, and are much less massive than the gas clumps born in the classical Gravitational Instability (GI) theory. It was recently suggested that such planets may form by the partial destruction of GI protoplanets: energy output due to the growth of a massive core may unbind all or most of the surrounding pre-collapse protoplanet.Here we present the first 3D global disc simulations that simultaneously resolve grain dynamics in the disc and within the protoplanet. We confirm that massive GI protoplanets may self-destruct at arbitrarily large separations from the host star provided that solid cores of mass ∼10-20 M ⊕ are able to grow inside them during their precollapse phase. In addition, we find that the heating force recently analysed by Masset & Velasco Romero (2017) perturbs these cores away from the centre of their gaseous protoplanets. This leads to very complicated dust dynamics in the protoplanet centre, potentially resulting in the formation of multiple cores, planetary satellites, and other debris such as planetesimals within the same protoplanet. A unique prediction of this planet formation scenario is the presence of sub-Jovian planets at wide orbits in Class 0/I protoplanetary discs.

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Section: Dynamics Of the Luminous Coresupporting

confidence: 86%

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores

Humphries

Nayakshin

2019

Monthly Notices of the Royal Astronomical Society

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“…We use the code PLANETALP (Ronco et al 2017;Guilera et al , 2019Guilera et al , 2020 to model the gas and dust disc evolution. To compute the growth of the planets, we coupled PLANETALP with the planet formation code developed by Venturini et al (2016).…”

Section: Methodsmentioning

confidence: 99%

Most super-Earths formed by dry pebble accretion are less massive than 5 Earth masses

Venturini

Guilera

Ronco

et al. 2020

A&A

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Aims. The goal of this work is to study the formation of rocky planets by dry pebble accretion from self-consistent dust-growth models. In particular, we aim to compute the maximum core mass of a rocky planet that can sustain a thin H-He atmosphere to account for the second peak of the Kepler size distribution. Methods. We simulate planetary growth by pebble accretion inside the ice line. The pebble flux is computed self-consistently from dust growth by solving the advection–diffusion equation for a representative dust size. Dust coagulation, drift, fragmentation, and sublimation at the water ice line are included. The disc evolution is computed solving the vertical and radial structure for standard α-discs with photoevaporation from the central star. The planets grow from a moon-mass embryo by silicate pebble accretion and gas accretion. We perform a parameter study to analyse the effect of a different initial disc mass, α-viscosity, disc metallicity, and embryo location. We also test the effect of considering migration versus an in situ scenario. Finally, we compute atmospheric mass loss due to evaporation over 5 Gyr of evolution. Results. We find that inside the ice line, the fragmentation barrier determines the size of pebbles, which leads to different planetary growth patterns for different disc viscosities. We also find that in this inner disc region, the pebble isolation mass typically decays to values below 5 M⊕ within the first million years of disc evolution, limiting the core masses to that value. After computing atmospheric mass loss, we find that planets with cores below ~4 M⊕ become completely stripped of their atmospheres, and a few 4–5 M⊕ cores retain a thin atmosphere that places them in the “gap” or second peak of the Kepler size distribution. In addition, a few rare objects that form in extremely low-viscosity discs accrete a core of 7 M⊕ and equal envelope mass, which is reduced to 3–5 M⊕ after evaporation. These objects end up with radii of ~6–7 R⊕. Conclusions. Overall, we find that rocky planets form only in low-viscosity discs (α ≲ 10−4). When α ≥ 10−3, rocky objects do not grow beyond 1 Mars mass. For the successful low-viscosity cases, the most typical outcome of dry pebble accretion is terrestrial planets with masses spanning from that of Mars to ~4 M⊕.

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“…where Ṁpeb is the accretion rate of pebbles onto the planet (see below). Depending on the accretion efficiency of the planet, this thermal torque can lead to outward migration (Guilera et al 2019;Baumann & Bitsch 2020).…”

Section: Migrationmentioning

confidence: 99%

How drifting and evaporating pebbles shape giant planets

Bitsch

2021

A&A

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Recent observations of extrasolar gas giants suggest super-stellar C/O ratios in planetary atmospheres, while interior models of observed extrasolar giant planets additionally suggest high heavy element contents. Furthermore, recent observations of protoplanetary disks revealed super-solar C/H ratios, which are explained by inward drifting and evaporating pebbles enhancing the volatile content of the disk. We investigate in this work how the inward drift and evaporation of volatile-rich pebbles influences the atmospheric C/O ratio and heavy element content of giant planets growing by pebble and gas accretion. To achieve this goal, we perform semi-analytical 1D models of protoplanetary disks, including the treatment of viscous evolution and heating, pebble drift, and simple chemistry to simulate the growth of planets from planetary embryos to Jupiter-mass objects by the accretion of pebbles and gas while they migrate through the disk. Our simulations show that the composition of the planetary gas atmosphere is dominated by the accretion of vapor that originates from inward drifting evaporating pebbles at evaporation fronts. This process allows the giant planets to harbor large heavy element contents, in contrast to models that do not take pebble evaporation into account. In addition, our model reveals that giant planets originating farther away from the central star have a higher C/O ratio on average due to the evaporation of methane-rich pebbles in the outer disk. These planets can then also harbor super-solar C/O ratios, in line with exoplanet observations. However, planets formed in the outer disk harbor a smaller heavy element content due to a smaller vapor enrichment of the outer disk compared to the inner disk, where the very abundant water ice also evaporates. Our model predicts that giant planets with low or large atmospheric C/O should harbor a large or low total heavy element content. We further conclude that the inclusion of pebble evaporation at evaporation lines is a key ingredient for determining the heavy element content and composition of giant planets.

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Thermal torque effects on the migration of growing low-mass planets

Cited by 42 publications

References 83 publications

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores

Most super-Earths formed by dry pebble accretion are less massive than 5 Earth masses

How drifting and evaporating pebbles shape giant planets

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