Abstract

The characterisation of exoplanet atmospheres is crucial to furthering our understanding of the physics that govern them. There are many approaches to how this can be accomplished, with advantages and drawbacks to each, but common to nearly all of them is the comparison of observational data with theoretical models. The accuracy of any given characterisation is therefore dependent on theoretical model employed, and any simplifying assumptions that go into producing it. One of the more widely adopted examples is local thermodynamic equilibrium (LTE). While an incredibly useful simplification, it only really applies under certain conditions, and ignoring this constraint puts the accuracy of any characterization at risk. It is therefore important to know when LTE is appropriate, and when to switch to the more physically realistic alternative, non-local thermodynamic equilibrium (NLTE), instead. In this talk, I will give a brief overview of the atmospheric modelling process with a focus on NLTE and when/where it is important to include it, discuss the high-resolution cross correlation (HRCC) method of atmospheric characterisation and its limits, and compare HRCC results with those of Doppler Tomography, an alternative analysis technique for studying emission spectroscopy.