Tidal Downsizing model. I. Numerical methods: saving giant planets from tidal disruptions

Abstract

Tidal Downsizing (TD) is a recently developed planet formation theory that supplements the classical Gravitational disc Instability (GI) model with planet migration inward and tidal disruptions of GI fragments in the inner regions of the disc. Numerical methods for a detailed population synthesis of TD planets are presented here. As an example application, the conditions under which GI fragments collapse faster than they migrate into the inner $a\sim$ few AU disc are considered. It is found that most gas fragments are tidally or thermally disrupted unless (a) their opacity is $\sim 3$ orders of magnitude less than the interstellar dust opacity at metallicities typical of the observed giant planets, or (b) the opacity is high but the fragments accrete large dust grains (pebbles) from the disc. Case (a) models produce very low mass solid cores ($M_{\mathrm{core}}<0.1$ Earth masses) and follow a negative correlation of giant planet frequency with host star metallicity. In contrast, case (b) models produce massive solid cores, correlate positively with host metallicity and explain naturally while giant gas planets are over-abundant in metals.

Submitted to MNRAS November 19 2014. Comments welcome

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• Planetary Population Synthesis and the Emergence of Four Classes of Planetary System Architectures
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• Probing the impact of varied migration and gas accretion rates for the formation of giant planets in the pebble accretion scenario
• Tidal Downsizing Model. IV. Destructive feedback in planets
• TW Hya: an old protoplanetary disc revived by its planet
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• The burst mode of accretion in massive star formation with stellar inertia
• DIPSY: A new Disc Instability Population SYnthesis, II. The Populations of Companions Formed Through Disc Instability
• Feedback-limited Accretion: Variable Luminosity from Growing Planets
• Calibrated Gas Accretion and Orbital Migration of Protoplanets in 1D Disc Models
• Searching for wide-orbit gravitational instability protoplanets with ALMA in the dust continuum
• The paradox of youth for ALMA planet candidates
• Planets, debris and their host metallicity correlations
• On the dynamics of pebbles in protoplanetary disks with magnetically-driven winds
• Observational Signatures of Planetary Tidal Disruption Events Around Solar-Mass Stars