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Title: Hot-start Giant Planets Form with Radiative Interiors

Abstract

In the hot-start core accretion formation model for gas giants, the interior of a planet is usually assumed to be fully convective. By calculating the detailed internal evolution of a planet assuming hot-start outer boundary conditions, we show that such a planet will in fact form with a radially increasing internal entropy profile, so that its interior will be radiative instead of convective. For a hot outer boundary, there is a minimum value for the entropy of the internal adiabat S {sub min} below which the accreting envelope does not match smoothly onto the interior, but instead deposits high entropy material onto the growing interior. One implication of this would be to at least temporarily halt the mixing of heavy elements within the planet, which are deposited by planetesimals accreted during formation. The compositional gradient this would impose could subsequently disrupt convection during post-accretion cooling, which would alter the observed cooling curve of the planet. However, even with a homogeneous composition, for which convection develops as the planet cools, the difference in cooling timescale will change the inferred mass of directly imaged gas giants.

Authors:
;  [1]
  1. Department of Physics and McGill Space Institute, McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada)
Publication Date:
OSTI Identifier:
22654393
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 846; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOUNDARY CONDITIONS; CONVECTION; ENTROPY; EVOLUTION; MIXING; PLANETS; SATELLITES

Citation Formats

Berardo, David, and Cumming, Andrew, E-mail: david.berardo@mcgill.ca, E-mail: andrew.cumming@mcgill.ca. Hot-start Giant Planets Form with Radiative Interiors. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA81C0.
Berardo, David, & Cumming, Andrew, E-mail: david.berardo@mcgill.ca, E-mail: andrew.cumming@mcgill.ca. Hot-start Giant Planets Form with Radiative Interiors. United States. doi:10.3847/2041-8213/AA81C0.
Berardo, David, and Cumming, Andrew, E-mail: david.berardo@mcgill.ca, E-mail: andrew.cumming@mcgill.ca. Sun . "Hot-start Giant Planets Form with Radiative Interiors". United States. doi:10.3847/2041-8213/AA81C0.
@article{osti_22654393,
title = {Hot-start Giant Planets Form with Radiative Interiors},
author = {Berardo, David and Cumming, Andrew, E-mail: david.berardo@mcgill.ca, E-mail: andrew.cumming@mcgill.ca},
abstractNote = {In the hot-start core accretion formation model for gas giants, the interior of a planet is usually assumed to be fully convective. By calculating the detailed internal evolution of a planet assuming hot-start outer boundary conditions, we show that such a planet will in fact form with a radially increasing internal entropy profile, so that its interior will be radiative instead of convective. For a hot outer boundary, there is a minimum value for the entropy of the internal adiabat S {sub min} below which the accreting envelope does not match smoothly onto the interior, but instead deposits high entropy material onto the growing interior. One implication of this would be to at least temporarily halt the mixing of heavy elements within the planet, which are deposited by planetesimals accreted during formation. The compositional gradient this would impose could subsequently disrupt convection during post-accretion cooling, which would alter the observed cooling curve of the planet. However, even with a homogeneous composition, for which convection develops as the planet cools, the difference in cooling timescale will change the inferred mass of directly imaged gas giants.},
doi = {10.3847/2041-8213/AA81C0},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 846,
place = {United States},
year = {Sun Sep 10 00:00:00 EDT 2017},
month = {Sun Sep 10 00:00:00 EDT 2017}
}