Gas flow around a planet embedded in a protoplanetary disc

Kuwahara, Ayumu; Kurokawa, Hiroyuki; Ida, Shigeru

doi:10.1051/0004-6361/201833997

Cited by 37 publications

(59 citation statements)

References 40 publications

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“…A key feature obvious in this figure is that the mass flow is oriented toward the core at high latitudes and away from the core in the equatorial plane. Every simulation presented in this paper displays such a global circulation, with the same orientation -outflow near the equatorial plane -as found by, e.g, Bate et al (2003), Fung et al (2015), Lambrechts & Lega (2017), Kuwahara et al (2019). The isodensity contours are pinched toward the core near the poles and outward in the equatorial plane.…”

Section: Flow Structuresupporting

confidence: 71%

“…This complicates the interpretation of the changes that occur as m c is varied, something that we do naturally here and in Paper I using a single setup for all values of m c . A notable exception is the recent study by Kuwahara et al (2019), who similarly explored the divide between subthermal and super-thermal mass cores using a single 3D isothermal numerical setup. The focus of their study was on exploring the evolution of the characteristics of the midplane outflow as m c was varied; in particular, they demonstrated a significant role played by the midplane outflow in preventing the accretion of solids by the core.…”

Section: Transition From Sub-thermal To Super-thermal Mass Regimesmentioning

confidence: 99%

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Envelopes of embedded super-Earths – II. Three-dimensional isothermal simulations

Béthune

Rafikov

2019

Monthly Notices of the Royal Astronomical Society

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Massive planetary cores embedded in protoplanetary discs are believed to accrete extended atmospheres, providing a pathway to forming gas giants and gas-rich super-Earths. The properties of these atmospheres strongly depend on the nature of the coupling between the atmosphere and the surrounding disc. We examine the formation of gaseous envelopes around massive planetary cores via three-dimensional inviscid and isothermal hydrodynamic simulations. We focus the changes in the envelope properties as the core mass varies from low (sub-thermal) to high (super-thermal) values, a regime relevant to close-in super-Earths. We show that global envelope properties such as the amount of rotational support or turbulent mixing are mostly sensitive to the ratio of the Bondi radius of the core to its physical size. High-mass cores are fed by supersonic inflows arriving along the polar axis and shocking on the densest parts of the envelope, driving turbulence and mass accretion. Gas flows out of the core's Hill sphere in the equatorial plane, describing a global mass circulation through the envelope. The shell of shocked gas atop the core surface delimits regions of slow (inside) and fast (outside) material recycling by gas from the surrounding disc. While recycling hinders the runaway growth towards gas giants, the inner regions of protoplanetary atmospheres, more immune to mixing, may remain bound to the planet.

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Section: Flow Structuresupporting

confidence: 71%

Section: Transition From Sub-thermal To Super-thermal Mass Regimesmentioning

confidence: 99%

Envelopes of embedded super-Earths – II. Three-dimensional isothermal simulations

Béthune

Rafikov

2019

Monthly Notices of the Royal Astronomical Society

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“…7a, b, e, and f). Since the planet chiefly perturbs the surrounding disk gas at a scale that is typically the smaller of the two when comparing the Bondi and Hill radii (Kuwahara et al 2019), the difference between UP-m001-hw01 and PI-Stokes-m001-hw01 cases can be seen in the region close to the planet. In particular, the accretion window is wider in the planet-induced gas flow than in the unperturbed flow when St = 10 −3 (Figs.…”

Section: Pebble Accretion In 2dmentioning

confidence: 99%

“…Recent hydrodynamical simulations have revealed that a planet embedded in a protoplanetary disk induces gas flow with a complex three-dimensional (3D) structure (Ormel et al 2015;Fung et al 2015Fung et al , 2019Lambrechts & Lega 2017;Cimerman et al 2017;Kurokawa & Tanigawa 2018;Kuwahara et al 2019;Béthune & Rafikov 2019). The anterior-posterior horseshoe flows extending in the orbital direction of the planet have a characteristic vertical structure that resembles a column.…”

Section: Introductionmentioning

confidence: 99%

Influences of protoplanet-induced three-dimensional gas flow on pebble accretion

Kuwahara

Kurokawa

2020

A&A

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Context. Pebble accretion is among the major theories of planet formation. Aerodynamically small particles, called pebbles, are highly affected by the gas flow. A growing planet embedded in a protoplanetary disk induces three-dimensional (3D) gas flow. In our previous work, Paper I, we focused on the shear regime of pebble accretion and investigated the influence of planet-induced gas flow on pebble accretion. In Paper I, we found that pebble accretion is inefficient in the planet-induced gas flow compared to that of the unperturbed flow, particularly when St ≲ 10−3, where St is the Stokes number. Aims. Following on the findings of Paper I, we investigate the influence of planet-induced gas flow on pebble accretion. We did not consider the headwind of the gas in Paper I. Here, we extend our study to the headwind regime of pebble accretion. Methods. Assuming a nonisothermal, inviscid sub-Keplerian gas disk, we performed 3D hydrodynamical simulations on the spherical polar grid hosting a planet with the dimensionless mass, m = RBondi∕H, located at its center, where RBondi and H are the Bondi radius and the disk scale height, respectively. We then numerically integrated the equation of motion for pebbles in 3D using hydrodynamical simulation data. Results. We first divided the planet-induced gas flow into two regimes: flow-shear and flow-headwind. In the flow-shear regime, where the planet-induced gas flow has a vertically rotational symmetric structure, we find that the outcome is identical to what we obtained in Paper I. In the flow-headwind regime, the strong headwind of the gas breaks the symmetric structure of the planet-induced gas flow. In the flow-headwind regime, we find that the trajectories of pebbles with St ≲ 10−3 in the planet-induced gas flow differ significantly from those of the unperturbed flow. The recycling flow, where gas from the disk enters the gravitational sphere at low latitudes and exits at high latitudes, gathers pebbles around the planet. We derive the flow transition mass analytically, mt, flow, which discriminates between the flow-headwind and flow-shear regimes. From the relation between m, mt, flow and mt, peb, where mt, peb is the transition mass of the accretion regime of pebbles, we classify the results obtained in both Paper I and this study into four groups. In particular, only when the Stokes gas drag law is adopted and m < min(mt, peb, mt, flow), where the accretion and flow regime are both in the headwind regime, the accretion probability of pebbles with St ≲ 10−3 is enhanced in the planet-induced gas flow compared to that of the unperturbed flow. Conclusions. Combining our results with the spacial variety of turbulence strength and pebble size in a disk, we conclude that the planet-induced gas flow still allows for pebble accretion in the early stage of planet formation. The suppression of pebble accretion due to the planet-induced gas flow occurs only in the late stage of planet formation, more specifically, in the inner region of the disk. This may be helpful for explaining the distribution of exoplanets and the architecture of the Solar System, both of which have small inner and large outer planets.

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“…Lee et al 2014), the continual recycling of the accreting gas around the planet (e.g. Ormel et al 2015;Cimerman et al 2017;Kurokawa & Tanigawa 2018;Kuwahara et al 2019), the delay of gas accretion by polluted envelopes (Brouwers & Ormel 2020), and disk dissipation (Ikoma & Hori 2012;Hori & Ogihara 2020). We have recently proposed the possibility of suppressing envelope accretion via a limit due to the disk accretion rate (Ogihara & Hori 2018), and similar solutions have been discussed in other studies (e.g.…”

Section: Introductionmentioning

confidence: 70%

Unified Simulations of Planetary Formation and Atmospheric Evolution: Effects of Pebble Accretion, Giant Impacts, and Stellar Irradiation on Super-Earth Formation

Ogihara

Hori

2020

ApJ

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A substantial number of super-Earths have been discovered, and atmospheres of transiting super-Earths have also been observed by transmission spectroscopy. Several lines of observational evidence indicate that most super-Earths do not possess massive H 2 /He atmospheres. However, accretion and retention of less massive atmospheres on super-Earths challenge planet formation theory. We consider the following three mechanisms: (i) envelope heating by pebble accretion, (ii) mass loss during giant impacts, and (iii) atmospheric loss by stellar X-ray and EUV photoevaporation. We investigate whether these mechanisms influence the amount of the atmospheres that form around super-Earths. We develop a code combining an N -body simulation of pebble-driven planetary formation and an atmospheric evolution simulation. We demonstrate that the observed orbital properties of super-Earths are well reproduced by the results of our simulations. However, (i) heating by pebble accretion ceases prior to disk dispersal, (ii) the frequency of giant impact events is too low to sculpt massive atmospheres, and (iii) many super-Earths having H 2 /He atmospheres of 10 wt% survive against stellar irradiations for 1 Gyr. Therefore, it is likely that other mechanisms such as suppression of gas accretion are required to explain less massive atmospheres ( 10 wt%) of super-Earths.

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Gas flow around a planet embedded in a protoplanetary disc

Cited by 37 publications

References 40 publications

Envelopes of embedded super-Earths – II. Three-dimensional isothermal simulations

Envelopes of embedded super-Earths – II. Three-dimensional isothermal simulations

Influences of protoplanet-induced three-dimensional gas flow on pebble accretion

Unified Simulations of Planetary Formation and Atmospheric Evolution: Effects of Pebble Accretion, Giant Impacts, and Stellar Irradiation on Super-Earth Formation

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