The FRIED grid of mass-loss rates for externally irradiated protoplanetary discs

Abstract

We present an open access grid of 3930 calculations of externally evaporating protoplanetary discs. This spans a range of disc sizes (1–400 au), disc masses, UV field strengths (10–104 G0), and stellar masses (0.05–1.9 M⊙). The grid is publicly available for download, and offers a means of cheaply including external photoevaporation in disc evolutionary calculations. It can also be queried using an online tool for quick estimates of instantaneous mass-loss rates (e.g for convenient evaluation of real observed systems). The ``fried'' grid itself illustrates that for discs around stars ≤0.3 M⊙, external photoevaporation is effective down to small radii (<50 au) down to UV fields at least as weak as 10 G0. At the other end of the scale, in a 104 G0 environment photoevaporation is effective down to 1 au even for stellar masses at least as high as 1.9 M⊙. We also illustrate in which regimes CO survives in the photoevaporative outflow for significant mass-loss rates; marking a system a good candidate to detect external photoevaporation in weak–intermediate UV environments through sub–Keplerian rotation. Finally, we make illustrative mass-loss rate estimates for discs in Taurus based on the Guilloteau et al. (2011) star–disc parameters, finding that around half are expected to have both significant mass-loss and retain CO in the photoevaporative outflow.