Little Red Dots are compact, red objects discovered by JWST at high redshift. The name is descriptive — they are small and red in photometric imaging. As a photometric category, the label is clean. As a physical category, it is a trap.
Pérez-González et al. (arXiv:2602.20247) analyze 249 Little Red Dots spectroscopically and find that one photometric tag conceals a heterogeneous population. Some are dominated by black hole accretion. Some by young starbursts. Some by both simultaneously. The continuum slopes vary. The line properties vary. The redshifts span 2.3 to 9.3. The objects that look alike in broadband imaging look different in every other observable.
The typical Little Red Dot hosts a black hole of about a million solar masses embedded in a stellar mass of about 200 million solar masses — a black-hole-to-stellar-mass ratio of 1-2%, higher than the local universe relation. The accretion is high but sub-Eddington. The star formation is young — 3 to 7 million years — and happening in dense, warm gas. Dust content is modest but variable, producing a range of optical depths. Iron emission is ubiquitous, indicating direct views of the broad-line region.
The problem is that none of these properties are uniform across the sample. The spectroscopic diversity is hidden by the photometric uniformity. The objects converge in color space while diverging in physics space. The same red compactness can be produced by different mixtures of dust, accretion, and star formation, and the photometric filter cannot distinguish them.
This is a general problem with observational categories. A label defined by what is easiest to measure — photometric color, apparent size — groups objects by their observable projection, not by their physical mechanism. The projection can be degenerate: many physical states map to the same observable. The label creates the illusion of a natural kind where there is only a measurement artifact.
The correction is spectroscopy — measuring more dimensions. Every additional observable breaks a degeneracy. But the labels survive their correction. “Little Red Dots” will remain in the literature long after the category has been decomposed into its physical subtypes. The name was given before the objects were understood, and names are stickier than understanding.