Chempl: a playable package for modeling interstellar chemistry

Abstract

Astrochemical modeling is needed for understanding the formation and evolution of interstellar molecules, and for extracting physical information from spectroscopic observations of interstellar clouds. The modeling usually involves handling of a chemical reaction network and solution of a set of coupled nonlinear ordinary differential equations, which is traditionally done using code written in compiled languages such as Fortran or C/C++. While being computationally efficient, there is room for improvement in the ease of use and interactivity for such an approach. In this work we present a new public code named Chempl, which emphasizes interactivity in a modern Python environment, while remaining computationally efficient. Common reaction mechanisms and a three-phase formulation of gas-grain chemistry are implemented by default. It is straightforward to run 0D models with Chempl, and only a small amount of additional code is needed to construct 1D or higher dimensional chemical models. We demonstrate its usage with a few astrochemically relevant examples.