Astronomers using the James Webb Space Telescope have identified a strange red object dating from 660 million years after the Big Bang that MIT researchers believe is a newly identified class of object: a black hole star, a massive black hole wrapped in a dense hydrogen gas cocoon that shines with the power of 100 billion stars while outshining its host galaxy.
Discovery of MoM-BH*-1 in Early Universe Fields
Researchers hunting for early galaxies in one of the deepest fields ever imaged by the NASA/ESA/CSA James Webb Space Telescope spotted a strange bright red spot hiding in plain sight. According to MIT astronomer Rohan Naidu, the source was labeled MoM-BH*-1 and was discovered as part of the telescope’s Mirage or Miracle survey. The object was essentially invisible in Webb’s bluer filters but blazed in the redder ones, displaying one of the most extreme colors ever recorded in a distant object. The discovery was described in a paper published in the journal Nature.
Since the telescope went online in 2022, it has spotted many extremely bright cosmic objects dubbed “little red dots” in the early universe that have baffled scientists. “What exactly these objects are has been one of the most debated topics of the JWST era,” Dr. Naidu said in a statement reported by CTV News and CBS News. The research team had initially been trying to find clues for why the telescope keeps finding bright galaxies in the universe’s infancy, a time when scientists thought it was too early for such massive formations to exist.
Spectroscopic Analysis and the Balmer Break Mystery
Follow-up spectroscopy revealed why the object displayed such an extreme color, showing the strongest “Balmer break” ever measured at any redshift. This sharp drop in brightness at a wavelength is normally associated with dense gas in the outer layers of stars. However, MIT researchers note that typical stellar populations—even the reddest ones known—reach less than a third of the intensity observed in MoM-BH*-1, meaning standard starlight cannot account for such a drastic drop.
“The break we observed in this object is the deepest break we have ever observed in any object, ruling out ‘ordinary’ stars as the source,” Dr. Naidu said. “But it made us wonder if we were seeing a new kind of ‘stellar atmosphere,’ but on a spectacular scale.”
The spectrum also showed unusually broad emission from hydrogen gas alongside deep absorption features cutting through that emission. This combination points to gas far denser than anything found in a typical star. Furthermore, the object’s light contained almost no signature of metals or elements other than hydrogen and helium. Robert Simcoe, a study co-author from the Massachusetts Institute of Technology, noted that while astronomers often assume distant red objects are surrounded by dust like soot or ash, the data showed that hydrogen gas—rather than dust—made the object appear red.
Modeling the Black Hole Star Structure
To explain the unusual pattern, researchers modeled the object as a massive black hole with a mass between 100,000 and 10 million times that of the Sun. This black hole is wrapped in an extraordinarily dense, turbulent envelope of hydrogen gas roughly 10 to 100 astronomical units across, placing it on the scale of our Solar System. The object’s peculiar spectral signature is created without requiring dust for its redness, as the gaseous cocoon absorbs and scatters the illumination filtering outward from the black hole’s accretion disk.
Pro Tip: Understanding Black Hole Stars
While standard stars are powered by nuclear fusion at their centers and typical black holes grow by consuming matter via an accretion disk, black hole stars represent a nascent black hole enshrouded in a dense gas envelope so that they radiate in a star-like manner, looking like a star the size of the solar system while producing vastly more energy.
The light output of MoM-BH*-1 vastly exceeds what nuclear fusion could generate at that size, according to study findings published in Nature. This eliminates the possibility of a conventional star and points instead toward a rapidly feeding black hole expanding at or past the Eddington limit, which represents the maximum theoretical rate at which matter can fall inward before the object’s own radiation pushes it outward. Scientists also detected tentative evidence that the object brightened by around 30% over roughly two months, representing another hallmark of active black hole feeding.
Frequently Asked Questions
What is a black hole star?
A black hole star is a newly identified class of astronomical object consisting of a central black hole—roughly 100,000 to 10 million times the mass of the Sun—wrapped in a massive, dense cocoon of hydrogen gas the size of our Solar System. It radiates star-like light powered by accretion rather than nuclear fusion.
How was MoM-BH*-1 discovered?
Astronomers spotted the object using the James Webb Space Telescope while hunting for early galaxies in the universe as part of the Mirage or Miracle survey, published in the journal Nature by Rohan Naidu and colleagues.
Why do scientists think there are more black hole stars?
The research team named the object MoM-BH*-1, where the designation indicates a black hole star and the number one suggests they believe similar objects are widespread. Dr. Naidu noted that “every little red dot is consistent with being a black hole star.”
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