Formation of Giant Planets

By G. D’Angelo, Jack J. Lissauer. 2004

445 citations recorded by the source corpus.

This is a descriptive and non-mathematical summary of giant planet formation theories. There are two end-member models, core accretion and disk instability. In the core accretion model, several to ten Earth masses of solid (ice and rock) accumulate and this promotes subsequent gas accretion. In the disk instability model, a self-gravitating sphere of gas forms (somewhat analogous to star formation) and a core may arise through condensation and rainout from its low density envelope. The core accretion model may have a time-scale difficulty because the formation of the embryo and infall of gas is not fast relative to the time at which the gaseous disk is removed. The disk instability model suffers from the current theoretical inability to follow the development of these putative instabilities through to the formation of a planet. Observational data on core masses in Jupiter and Saturn do not clearly favor one model. However, the existence and nature of Uranus and Neptune strongly suggest that the formation of appropriate embryos occurs. Moreover, there is considerable flexibility in the elapsed time required to form Jupiter and Saturn by the core accretion model, including times of only a few million years, compatible with disk lifetimes. This suggests that core accretion remains the favored mode in our solar system. It is possible that both mechanisms operate in general and that many extrasolar planetary systems make use of the disk instability mode. Future theory and observations are essential for deciding this issue.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2b614e9c1ea97d4d0c62dd713c5423f6d5e97bac

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Citations in the corpus

Synthetic Spectra and Colors of Young Giant Planet Atmospheres: Effects of Initial Conditions and Atmospheric Metallicity (2008, methodology): “Although this type of model has been successfully applied to Jupiter for decades (e.g., Graboske et al. 1975; Hubbard 1977; Guillot et al. 1995; Fortney & Hubbard 2003) their application to planets at very young ages could potentially be suspect (Stevenson 1982).”
On the Luminosity of Young Jupiters (2006, background): “Stevenson (1982) wrote that evolution calculations “...cannot be expected to provide accurate information on the first 105–108 years of evolution because of the artificiality of an initially adiabatic, homologously contracting1 state.””
Atmospheres of Protoplanetary Cores: Critical Mass for Nucleated Instability (2004, background): “Stevenson (1982) was the first to notice thatMcr is a sensitive function of the atmospheric composition in his study of purely radiative atmospheres.”
Separating gas-giant and ice-giant planets by halting pebble accretion (2014, background): “This occurs in practice when the mass bound in the envelope is comparable to the mass of the core and the self-gravity of the gas atmosphere becomes important (Stevenson 1982).”
Detailed Models of Super-Earths: How Well Can We Infer Bulk Properties? (2007, methodology): “There have been useful mass-radius relationships obtained with zero-temperature sphere models (Zapolsky & Salpeter 1969; Stevenson 1982; Fortney et al. 2006) that hint to the bulk composition of a planet.”
Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres (2007, background): “…Teff cooling calculations only match observed parameters for Jupiter (e.g, Hubbard 1977); Saturn is hotter than expected (Pollack et al. 1977; Stevenson & Salpeter 1977; Fortney & Hubbard 2003) and Uranus and Neptune are colder than expected (Stevenson 1982; Podolak et al. 1991; Guillot 2005).”
A FRAMEWORK FOR CHARACTERIZING THE ATMOSPHERES OF LOW-MASS LOW-DENSITY TRANSITING PLANETS (2013, background): “This must be critically kept in mind, since it has been shown (Hori & Ikoma 2011) that the enrichment of the envelope lowers the critical core masses and speeds up gas accretion (see also Stevenson 1982).”
Mass-Radius Relationships for Solid Exoplanets (2007, background): “In the past Stevenson (1982) and more recently Fortney et al. (2007) and Sotin et al. (2007) have also investigated mass-radius relationships of rocky and icy exoplanets.”
Internal structure of massive terrestrial planets (2005, background): “Su h a retion ould qui kly turn into a runaway pro ess that would lead to the formation of a gas giant planet like Jupiter (Mizuno 1980, Stevenson 1982, Bodenheimer and Polla k 1986).”
MAKE SUPER-EARTHS, NOT JUPITERS: ACCRETING NEBULAR GAS ONTO SOLID CORES AT 0.1 AU AND BEYOND (2014, background): “The theory states that a solid core of rock and metal, when embedded in a gas-rich nebula, undergoes “runaway gas accretion” to become a gas giant like Jupiter, if the core mass is sufficiently large (Perri & Cameron 1974; Harris 1978; Mizuno et al. 1978; Mizuno 1980; Stevenson 1982).”
A FRAMEWORK FOR QUANTIFYING THE DEGENERACIES OF EXOPLANET INTERIOR COMPOSITIONS (2009, background): “In addition, significant scatter in the observationally determined planetary masses and radii further hampers a comparative study of the transiting hot Neptunes’ possible interior compositions.”
Models of Jupiter's growth incorporating thermal and hydrodynamic constraints (2008, background): “According to the core nucleated accretion model, giant planets begin their growth via the same process of agglomeration of solid bodies as do terrestrial planets; however, unlike terrestrials, the solid cores of giant planets reach masses large enough to capture substantial amounts of gas from their”
Toward a Deterministic Model of Planetary Formation. III. Mass Distribution of Short-Period Planets around Stars of Various Masses (2005, background): “As the cores grow beyond a mass Mc,hydro ≃ 10 ( Ṁc 10−6M⊕/yr )0.25 M⊕, (9) their planetary atmosphere is no longer in hydrodynamic equilibrium and they begin to accrete gas (Stevenson 1982; Ikoma et al. 2000).”