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Small red dot observed by James Webb gathers signals used by astronomers to investigate black holes in the distant universe, with deep spectrum, gravitational lens, and more than 40 lines that help analyze one of the still little-understood structures of the cosmos.
The James Webb Space Telescope identified evidence supporting the hypothesis that some “small red dots”, compact objects observed in the distant universe, are growing black holes surrounded by dense gas.
Among the analyzed cases, GLIMPSE-17775 is one of the most detailed so far and was studied by a team led by Vasily Kokorev, a researcher at the University of Texas at Austin.
Released on June 10, 2026, the study describes the deepest spectrum ever obtained of such an object, according to the scientific publication on the observation.
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The team identified more than 40 spectral lines in a small red source observed by Webb, which allowed for comparing models about the nature of these objects with a larger volume of data.
The small red dots began to be investigated more closely after the start of Webb’s scientific operations in 2022, when the telescope began revealing compact and reddish objects in the early universe.
According to ESA, these objects were observed in periods close to 600 million years after the Big Bang, a phase in which the formation of galaxies, stars, and black holes is still under study by astronomy.
In the case of GLIMPSE-17775, the analyzed source is not described as an object observed only 600 million years after the Big Bang.
The estimate cited in the study places GLIMPSE-17775 at a stage of about 1.8 billion years after the Big Bang, due to the cosmological redshift of 3.5.
What Webb observed in GLIMPSE-17775
Located behind the galaxy cluster Abell S1063, GLIMPSE-17775 was observed in a position that allowed researchers to take advantage of the gravitational lens effect.
This phenomenon occurs when the gravity of a massive object, such as a galaxy cluster, magnifies and distorts the light from more distant sources in the observer’s field of view.
The magnification was relevant for the analysis because Webb obtained a 30-hour spectrum, but the gravitational lens effect made the result comparable to about 80 hours of observation.
With this gain, the team managed to separate spectral signals that would be more difficult to detect in a small, weak source located at a great cosmological distance.
Spectral lines act as records of the interaction between light and matter, allowing the identification of chemical elements and inferring physical characteristics of the environment around the observed source.
Through these lines, astronomers analyze how light was emitted, absorbed, or scattered by atoms, ions, and molecules present in the object or its surroundings.
In the spectrum of GLIMPSE-17775, researchers found signals associated with hydrogen, oxygen, helium, sulfur, and iron, elements used in the physical interpretation of the source.
According to NASA, many of these lines do not fit well into a simple model of a rotating gas cloud and are more compatible with electron scattering in hot, dense gas.
Why scientists talk about a star with a black hole
The expression “star with a black hole” is used as a reference to a proposed model to explain small red dots, and not to a common star similar to the Sun.
In this scenario, the object would be a rapidly growing supermassive black hole, surrounded by a dense cocoon of partially ionized gas, according to the interpretation presented by the researchers.
The gas around the source would reprocess the light emitted near the black hole, altering the observed spectrum and contributing to the red and compact appearance of these objects.
This same structure is also pointed out as a possible explanation for the low X-ray emission of many small red dots, as part of the radiation could be absorbed by the gas.
Kokorev stated that part of the scientific community has considered models of stars with black holes to explain the small red dots observed by Webb.
According to the researcher, no previously analyzed object gathered, in the same data set, as much evidence associated with this interpretation as GLIMPSE-17775.
Commenting on the initial analysis of the spectrum, Kokorev compared the work to assembling a puzzle, where each measured line helped to compose a physical interpretation of the source.
The team measured the signals, compared the identified emissions, and organized the data into a model that supports the hypothesis of a growing black hole within a dense gaseous environment.
Spectral lines reinforce hypothesis about black hole
Among the signals described by the team are iron lines that form the set called by the researchers “iron forest”, a feature used in the interpretation of the spectrum.
The intensity and the relationship between these lines, combined with oxygen signals, were identified in the study as compatible with an intense energy source, such as a rapidly accreting black hole.
Evidence of helium fluorescence and absorption was also observed, two elements that researchers associate with the presence of a dense medium surrounding an energy source.
The combination of these signals placed GLIMPSE-17775 among the objects used to test the hypothesis that small red dots may harbor growing black holes.
Another aspect analyzed involves the so-called Balmer break, a drop in light emission related to common characteristics identified in small red dots.
In GLIMPSE-17775, this signal appears weaker than expected, and the team used complementary data from the Hubble’s Frontier Fields and BUFFALO programs to evaluate the host galaxy.
According to the interpretation presented by the researchers, a giant host galaxy around the object may contribute additional blue light and smooth out the Balmer break.
This explanation was considered by the team without ruling out the gas cocoon model, which remains among the hypotheses used to interpret the spectrum of GLIMPSE-17775.
Discovery helps to investigate the primitive universe
GLIMPSE-17775 gained scientific relevance because it gathers, in a single object, signals that had been partially observed in other small red dots.
For the team responsible for the study, this concentration of evidence offers an opportunity to investigate how supermassive black holes may have grown in ancient phases of the universe.
Despite the gathered evidence, the hypothesis that the object harbors a black hole does not conclude the discussion about the origin and nature of the small red dots.
Kokorev stated that the researchers believe it to be a black hole, but acknowledged that other theories remain under discussion to explain the central engine of these objects.
New observations may help differentiate the models in debate and clarify which physical processes fuel the small red dots observed by James Webb.
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