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

TL;DR

This paper introduces the FRIED grid, a comprehensive set of calculations for external photoevaporation of protoplanetary discs, enabling easier inclusion of these effects in disc evolution models and observational analysis.

Contribution

The paper provides the first extensive, publicly available grid of 3930 calculations covering various disc and environmental parameters for external photoevaporation modeling.

Findings

Photoevaporation is effective down to small radii for low-mass stars in weak UV fields.

In strong UV environments, photoevaporation affects discs down to 1AU even for higher-mass stars.

CO can survive in the outflow in certain regimes, aiding observational detection.

Abstract

We present an open access grid of 3930 calculations of externally evaporating protoplanetary discs. This spans a range of disc sizes (1-400AU), disc masses, UV field strengths (10-10$^4$G$_0$) and stellar masses (0.05-1.9M$_\odot$). 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 $\leq0.3$M$_\odot$ external photoevaporation is effective down to small radii ($<50$AU) down to UV fields at least as weak as 10G$_0$. At the other end of the scale, in a $10^4$G$_0$ environment photoevaporation is effective down to 1AU even for stellar masses at least as high as 1.9M$_\odot$. 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.