THE TWO MODES OF GAS GIANT PLANET FORMATION

By Aaron C. Boley. 2009

205 citations recorded by the source corpus.

I argue for two modes of gas giant planet formation and discuss the conditions under which each mode operates. Gas giant planets at disk radii r>100 AU are likely to form in situ by disk instability, while core accretion plus gas capture remains the dominant formation mechanism for r < 100 AU. During the mass accretion phase, mass loading can push disks toward fragmentation conditions at large r. Massive, extended disks can fragment into clumps of a few to tens of Jupiter masses. This is confirmed by radiation hydrodynamics simulations. The two modes of gas giant formation should lead to a bimodal distribution of gas giant semimajor axes. Because core accretion is expected to be less efficient in low-metallicity systems, the ratio of gas giants at large r to planets at small r should increase with decreasing metallicity.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6a41f46c29f944f6bf613496e33cf5d7387fb66a

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Citations in the corpus

CHALLENGES IN FORMING PLANETS BY GRAVITATIONAL INSTABILITY: DISK IRRADIATION AND CLUMP MIGRATION, ACCRETION, AND TIDAL DESTRUCTION (2011, methodology): “Boley 2009 has done four simulations with similar mass loading as our simulations, two of which (SIMB and SIMD) can be compared with our simulations.”
Imaging Extrasolar Giant Planets (2016, background): “…should resemble that of binary stars; disk instability and core accretion may result in a bimodal period distribution for giant planets (Boley 2009); planet scattering to wide orbits should produce a rising mass function at low planet masses as opposed to a truncated mass distribution…”
THE BURST MODE OF ACCRETION AND DISK FRAGMENTATION IN THE EARLY EMBEDDED STAGES OF STAR FORMATION (2010, background): “The time-averaged rate of mass accretion onto the disk 〈Ṁd〉 is greater than the time-averaged mass accretion onto the star 〈Ṁ∗〉 so that Σ quickly increases with time and may reach the unstable regime (Vorobyov & Basu 2006, 2007; Vorobyov 2009b; Kratter et al. 2010; Boley 2009).”
Dynamics of Protoplanetary Disks (2010, background): “The first two modes are relevant to disk evolution, while the possibility of fragmentation is of great interest as a mechanism for forming massive planets or substellar objects (Boley 2009; Boss 1997; Stamatellos, Hubber & Whitworth 2007).”
PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS. II. EXTENSION TO FAINTER SOURCES (2010, background): “Even without invoking some kind of mass loading mechanism (Boley 2009), viscous evolution implies that these disks originally had denser, more compact structures, which might suggest a formerly lower minimum Q-value and/or radius where the disk is least stable to fragmentation.”
A torque formula for non-isothermal type I planetary migration – I. Unsaturated horseshoe drag (2009, background): “An alternative scenario involves direct fragmentation of the disc (Boss 1997), which is probably only possible in the outermost regions of the disc (Boley 2009).”
Extrasolar planet population synthesis - IV. Correlations with disk metallicity, mass, and lifetime (2012, background): “Also for the direct collapse model this case is probably not obvious to explain due to the small semimajor axis of the planets (about 1.5 AU for the inner planet), see e.g. Boley (2009).”
TOWARD CHEMICAL CONSTRAINTS ON HOT JUPITER MIGRATION (2014, background): “Core accretion of gas onto a∼10 M⊕ solid core operates within ∼1-10 AU (Pollack et al. 1996; Lissauer & Stevenson 2007), while rapid collapse by gravitational instability may occur beyond a few tens of AU (Boss 2000; Gammie 2001; Boley 2009).”
Our astrochemical heritage (2012, methodology): “Different results are found by Ilee et al. (2011), who used the hydrodynamic simulations of a young and relatively massive (0.39 M ) disk by Boley (2009) as input in their gas-phase and simple surface chemistry network.”
RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, background): “Moreover, this disk instability mechanism seems to naturally favor formation at wide separations from the primary (Boss 2006; Boley 2009; Rafikov 2009; Clarke 2009; Dodson-Robinson et al. 2009).”
Clumps in the outer disk by disk instability: Why they are initially gas giants and the legacy of disruption (2009, methodology): “This topic warrants further study, but we only emphasize this as a real possibility during the early phases of disk evolution while heavy infall is present on the disk (Vorobyov and Basu, 2006; Boley, 2009).”
PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, background): “…collapse of a massive protoplanetary disk has consumed much of the discussion about planet formation for the past decade, especially after the discovery of the HR 8799 planets (e.g., Boss 2007; Durisen et al. 2007; Boley 2009; Dodson-Robinson et al. 2009; Nero & Bjorkman 2009; Kratter et al. 2010).”
THE FORMATION MECHANISM OF GAS GIANTS ON WIDE ORBITS (2009, unknown): “Boley (2009) argues for two modes of planet formation, with core accretion dominating near the star and disk instability forming a population of gas giants at large radii.”
LkCa 15: A YOUNG EXOPLANET CAUGHT AT FORMATION? (2011, background): “In contrast, disk instability models are more efficient at forming planets at larger radii (a >25–50 AU) (Rafikov 2005; Boley 2009; Meru & Bate 2010; Boss 2011) since they are primarily limited by the ability of gas to efficiently cool and by the shear of differential rotation speeds, both of which…”
THE TW Hya DISK AT 870 μm: COMPARISON OF CO AND DUST RADIAL STRUCTURES (2011, background): “If true, gas densities at large disk radii may be higher than typically assumed, with profound implications for facilitating giant planet formation by gravitational instability (e.g., Boley 2009; Kratter et al. 2010; Boss 2011).”
THE RUNTS OF THE LITTER: WHY PLANETS FORMED THROUGH GRAVITATIONAL INSTABILITY CAN ONLY BE FAILED BINARY STARS (2009, background): “While more numerical follow up will be necessary to pin down the true distribution of fragments born through GI, at present simulations show that this estimate may well be a lower limit, but is the correct order of magnitude (Boley 2009; Stamatellos & Whitworth 2009).”
THE EFFECTS OF RADIATIVE TRANSFER ON LOW-MASS STAR FORMATION (2009, background): “However, bursty accretion due to disk instability also depends upon the core rotation and the rate at which mass is fed into the disk from the envelope(Vorobyov & Basu 2006; Boley 2009).”