Black Holes or 'Black Hole Stars'? Astronomers Clash Over Webb's Little Red Dots

The James Webb Space Telescope was built to capture faint light from the universe's first billion years after the Big Bang. In its earliest images, astronomers spotted objects that glowed blindingly bright and red, as luminous as a galaxy despite spanning only a pixel. In 2023 researchers named them "little red dots."

Astronomers first thought the dots were distant galaxies, but such bright galaxies would have to be implausibly massive so early in the universe, earning them the nickname "universe breakers." Closer study, the Rubies survey (Red Unknowns: Bright Infrared Extragalactic Survey) led by Anna de Graaff of the Max Planck Institute for Astronomy in Heidelberg, Germany, and the MOM survey (Mirage or Miracle) co-led by Rohan Naidu of the University of Hawai'i, found the dots' hydrogen light smeared across many colors, a "broad line" produced when gas whips around a black hole. Many astronomers concluded the dots hid supermassive black holes reddened by dust, though most did not flicker or emit X-rays.

In spring 2025, de Graaff's and Naidu's teams independently reported two little red dots unlike any object ever seen. "In all the millions of [observations] we've taken with ground-based telescopes, there's nothing that looks like these sources," de Graaff said. The dots showed almost no blue light, and their spectra jumped sharply brighter at one red wavelength, a "Balmer break," typically seen in hot hydrogen gas such as stars.

The teams proposed the dots are a new kind of object, a "black hole star": hydrogen glowing with the light of billions of suns around a hidden black hole. A paper posted last week argued Webb is witnessing the births of supermassive black holes inside such colossal stars. "There is a fundamentally new phenomenon afoot," said Naidu.

Not everyone agrees, and the claim has triggered follow-up research and a sharp debate. "The field has gotten very polarized," said Anna-Christina Eilers, an astrophysicist at the Massachusetts Institute of Technology.