iota Hor SED modelling

This leads to consistently stronger helium signatures during maximum phases. We show that planets at the largest orbit are more affected by cycles, showing larger variations in escape rates and absorptions between minimum and maximum. We also confirm the counter-intuitive behaviour that, despite the fall-off in escape rate with orbital distance, the HeI 1083nm absorption is not significantly weaker at further orbits, even strengthening with orbital distance for some iota Hor planets.

We partially explain this behaviour with the lower mid-UV fluxes at more distant orbits, leading to less HeI(23S) photoionisations. Finally, we propose that stellar cycles could explain some of the conflicting HeI 1083nm observations of the same planet, with detections more likely during a phase of activity maximum.