Correlation plots. Targets are from this work, Guilluy et al. (2020, 2023), and Fossati et al. (2022). Contrast c (left panels) and ${\delta }_{{\text{R}}_{\text{P}}}/H_{\text{eq}}$ (right panels) as a function of the EUV flux in the 200–504 Å range, effective temperature and planetary gravity, and log R′_HK. Red markers indicate targets with only an upper limit on the He I detection (reported at 1σ). The vertical dashed blue lines in the effective temperature diagrams indicate the transition from M-type to K-type stars. The dashed horizontal line connects the two possible locations for HAT-P-3b (for the two different coronal temperatures).