- Andrey Yachmenev
- Emil Zak
title: 'The ExoMol database: molecular line lists for exoplanet and other hot atmospheres'
---

infrared ,visible ,Einstein $A$ coefficients ,transition frequencies ,partition functions ,cooling functions ,lifetimes ,cross sections ,$k$ coefficients ,Landé $g$-factors

Introduction
============

Hot molecules exist in many environments in space including cool stars [@09Bexxxx.exo], failed stars generally known as brown dwarfs [@aha97; @09Bexxxx.exo] and exoplanets [@13TiEnCo.exo]. The atmospheric properties of these objects are known to be strongly influenced by the spectra of the molecules they contain. On Earth, spectra of hot molecules are observed in flames [@14BoWeHy; @15CoLixx], discharge plasmas [@02ChWaLi.SO; @15BiCrGl], explosions [@11CaLiPi.H2O] and in the hot gases emitted, for example, from smoke stacks [@12EvFaCl.CO2]. In addition, high-lying states can be important in non local thermodynamic equilibrium (LTE) environments both in space, for example, emissions observed from comets [@jt330; @jt349], and on Earth. The spectra of key atmospheric molecules at room temperature have been the subject of systematically maintained databases such as HITRAN [@jt350; @jt453; @jt546] and GEISA [@jt504; @jtGEISA]. As will be amply illustrated below, the spectra of hot molecules contain many, many more transitions and so far attempts to compile systematic databases have been limited. Databases of hot molecular 