Supermassive Stars Match the Spectral Signatures of JWST’s Little Red Dots

Abstract The James Webb Space Telescope (JWST) has unveiled a population of enigmatic, compact sources at high redshift known as “little red dots” (LRDs), whose physical nature remains a subject of intense debate. Concurrently, the rapid assembly of the first supermassive black holes (SMBHs) requires the formation of heavy seeds, for which supermassive stars (SMSs) are leading theoretical progenitors. In this work, we perform the first quantitative test of the hypothesis that LRDs are the direct observational manifestation of these primordial SMSs. We present a novel, first-principles pipeline generating synthetic spectra for a nonrotating, metal-free SMS up to 10 6 M ⊙ . We establish that its luminosity ( L λ…