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

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.