FUV flux inferred distribution in Orion stars

We compared the results with population synthesis models of viscous discs experiencing external photoevaporation. We provided a publicly available table of FUV fluxes at ~8600 stars in Orion. Most of this stellar population is weakly FUV-irradiated, <10^2^ G0, ~35% is intermediately irradiated, 10^2^-10^4^ G0, and only ~5% has FUV fluxes >10^4^ G0.

Gaia-based Lacc decreases with age, and Halpha detection fraction declines more rapidly in regions with strong FUV fluxes (>10^2^ G0) than in regions exposed to weaker FUV fluxes (<10^2^ G0), broadly consistent with the model. This result may suggest that external photoevaporation efficiently depletes strongly FUV-irradiated accretion discs, but it is not sufficient to reliably confirm this conclusion. The tools we provided for accurately computing FUV fluxes at the Orion stellar population will be essential for targeting sources in future observations aimed at assessing the role of external photoevaporation on protoplanetary disc.

Our study highlights the need for additional measurements of stellar and disc properties across the Orion population, covering the FUV flux range 1-10^5^ G0.