Abstract

Photoevaporation driven by high energy radiation from the central star plays an important role in the evolution of protoplanetary discs. Photoevaporative winds have been unambiguously detected through blue-shifted emission lines, but their detailed properties remain uncertain. I will present a new empirical approach to make observational predictions of these thermal winds, seeking to fill the gap between theory and observations. In this work, we use a self-similar model of an isothermal wind to compute line profiles of several characteristic emission lines, studying how the lines are affected by parameters such as the gas temperature, disc inclinations, and density profile. We derive the typical observables as functions of the parameters of the model and compare our results with real data. When combined with new observations, these new diagnostics will allow us to build up a complete picture of how disc winds shape the evolution of planet-forming discs.