ThermoSNCC: a free tool for modeling condensation sequences

In the protoplanetary accretion disk, stellar nebula gas condenses into dust that then aggregates into mineral grains and eventually planetesimals. These condensation processes are key to our understanding of the formation of both our solar system and exoplanetary systems; yet no fast, open-source software is currently available for modeling condensation of nebular gas across the wide range of low (< 1 bar) pressures and high (up to 2000 K) temperatures predicted for the inner region of a protoplanetary disk (Cameron and Pine 1973, Icarus 18.3, 377-406; Desch et al. 2018, ApJS 238, 1), especially for the wide range of elemental compositions observed in stars other than the Sun (Hinkel et al. 2014, AJ 148, 54).

Here we present the Thermodynamic Solar Nebula Condensation Calculator (ThermoSNCC) as a free, open-source software toolset for cosmochemical thermodynamic modeling. It works by integrating a gas phase into the existing ENabling Knowledge Integration (ENKI) MELTS thermodynamic framework for solids and liquids (Ghiorso and Sack 1995, Contrib Mineral Petr 119, 197-212) and then minimizing the Gibbs free energy of the resulting multi-phase system. The goal of developing ThermoSNCC is to provide users a web-based interface to rapidly model the equilibrium state between an initial gas mixture, condensing minerals, and silicate melts along a customizable temperature-pressure trajectory. All underlying thermodynamic data used in calculations are open-source and available in a self-consistent, online public database maintained by ENKI.

Here, we apply ThermoSNCC to model condensation of elements in a gas of solar composition and compare results to previous predictions by Ebel 2006 (MESS-II, 1, 253-277) and others as a benchmark of its current state of development. Once ThermoSNCC is released to the public, features that model disequilibrium processes could be implemented, such as transport of material via kinetic convection and temperature-dependent fractionation of condensates.