An Atmospheric Structure Equation for Grain Growth

Abstract

We present a method to include the evolution of the grain size and grain opacity ${\kappa }_{\mathrm{gr}}$ in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size dominates the grain size distribution at any height $r$. In addition to following grain growth, the method accounts for mass deposition by planetesimals and grain porosity. We illustrate this method by computation of a simplified atmosphere structure model. In agreement with previous works, grain coagulation is seen to be very efficient. The opacity drops to values much below the often-used `ISM-opacities' ($\sim$$1{\mathrm{c}{\mathrm{m}}^2\mathrm{g}}^{-1}$) and the atmosphere structure profiles for temperature and density resemble that of the grain-free case. Deposition of planetesimals in the radiative part of the atmosphere hardly influences this outcome as the added surface is quickly coagulated away. We observe a modest dependence on the internal structure (porosity), but show that filling factors cannot become too large because of compression by gas drag.

6 pages; accepted for publication in APJ Letters

References in corpus (7)

• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Dust size distributions in coagulation/fragmentation equilibrium: Numerical solutions and analytical fits
• Dust coagulation in protoplanetary disks: porosity matters
• Formation of Jupiter using opacities based on detailed grain physics
• The opacity of grains in protoplanetary atmospheres
• Oligarchic planetesimal accretion and giant planet formation
• Solving the Coagulation Equation by the Moments Method

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