Disc evolution in different cluster environments

Planet forming discs typically survive for a few up to around ten million years. During this time the parent star still resides within its natal cluster and hence may be subject to environmental effects such as gravitational encounters (e.g. as in the case of RW Aur) or irradiation by other cluster members. Recent research has demonstrated that irradiation generally dominates (Winter et al. 2018). I'll present the latest results from a large programme of research into photoevaporation of discs as a function of UV field strength, stellar mass and disc mass/radius. This includes the upcoming FRIED grid of publicly available mass loss rates that will be valuable for viscous evolutionary models of discs and can also be used to compute the evolution of discs in star cluster formation and feedback calculations (Haworth et al. in prep). This grid can also be used to trivially estimate mass loss rates for real systems. I'll also demonstrate that the proto Trappist-1 disc-to-star mass ratio has to be high at ~0.3, but the disc is still expected to be stable. This has important consequences for models trying to explain the observed Trappist-1 planets (Haworth et al. 2018)