Suppression of atmospheric recycling of planets embedded in a protoplanetary disc by buoyancy barrier
Year: 2018
Type: article
Abstract: The ubiquity of super-Earths poses a problem for planet formation theory to explain how they avoided becoming gas giants. Rapid recycling of the envelope gas of planets embedded in a protoplanetary disc has been proposed to delay the cooling and following accretion of disc gas. We compare isothermal and non-isothermal 3D hydrodynamical simulations of the gas flow past a planet to investigate the influence on the feasibility of the recycling mechanism. Radiative cooling is implemented by using the β cooling model. We find that, in either case, gas enters the Bondi sphere at high latitudes and leaves through the mid-plane regions, or vice versa when disc gas rotates sub-Keplerian. However, in contrast to the isothermal case where the recycling flow reaches the deeper part of the envelope, the inflow is inhibited from reaching the deep envelope in the non-isothermal case. Once the atmosphere starts cooling, buoyant force prevents the high-entropy disc gas from intruding the low-entropy atmosphere. We suggest that the buoyancy barrier isolates the lower envelope from the recycling and allows further cooling, which may lead runaway gas accretion on to the core.
Authors: Hiroyuki Kurokawa, Takayuki Tanigawa
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
Awards: Revealing icy pebble accretion and water content of terrestrial planets by hydrodynamic simulations of protoplanetary disks, Constructing a standard formation model of satellites around gas giant planets, G5207093753, 地球と系外地球型惑星の大気形成過程及びマントルと大気の化学的共進化の理論的研究, Origin of satellite systems around giant planets: Supply of building material of satellites to circumplanetary disks
OpenAlex ID: W2807085682