Hertzsprung–Russell (H-R) diagram of LRDs: the peak wavelength (λ_peak) of the optical-to-near-infrared, blackbody-like continuum as a function of its luminosity (L_bb). The top axis indicates the effective temperature of a blackbody peaking at λ_peak, based on Wien’s displacement law. Dashed gray lines mark loci of constant blackbody radius (in astronomical units), derived by combining L_bb = 4πR²σT⁴ with the Stefan–Boltzmann law. The JWST LRD sample is compiled from A. de Graaff et al. (2025a) and B. Wang et al. (2026).