Black hole stars may be real, according to astronomers who have studied a hybrid object exhibiting characteristics of both stars and black holes. The object, formally known as MoM-BH-1, was analysed and the results published this week in the journal Nature.
From the outside, the object bears a striking resemblance to a star, thanks to its outer shell of very hot and dense gas. It exhibits other star-like behaviours as well, particularly when observed with the NIRSpec instrument on NASA’s James Webb Space Telescope.
What sets MoM-BH-1 apart
There are notable differences when the object is compared with conventional stars. MoM-BH-1 has a black hole at its centre rather than the molten core of a traditional star. It is also the size of our entire solar system and puts out more than 100 billion times the amount of energy of any known star. That energy output is more in line with measurements taken from black holes, and the object displays traits unlike anything previously observed.
These features led researchers, including Naidu, to consider that the object might be something entirely new. They were not searching for a black hole star at all. The team was using the telescope to seek out the oldest galaxies in the known universe and to learn more about how they formed. Naidu believes they may have uncovered two pieces of the puzzle at once, as these black hole stars could have played a role in the formation of early galaxies.
“These are not stars in a literal sense,” Naidu explained. “These are objects that show features traditionally associated with black holes as well as those classically seen in stars. The physical configuration that can produce these hybrid features involves a dense cocoon of gas enveloping the black hole.”
According to Naidu, the black hole is likely consuming material on the inside of the star. In this case, the cocoon of dense gas acts as a substitute for the standard accretion disc, which is the accumulated material encircling a black hole before it is consumed. A star is a dense ball of gas powered by nuclear fusion, and black holes typically have accretion discs that feed them. A black hole star has a dense ball of gas, like a star, but uses a black hole as a power source.
A possible answer to the little red dot mystery
The James Webb Space Telescope launched in 2021 and began observing the universe in July 2022. It almost immediately started finding a series of mysterious objects that researchers call little red dots, since that is how they appear in scans. Research has turned up 341 little red dots to date, and owing to limitations of the telescope’s instruments, researchers have not been able to determine what they are.
“These little red dots seem to be everywhere in the early universe, but essentially disappear by the present day,” Naidu said. “What exactly these objects are has been one of the most debated topics of the JWST era.”
The characteristics of MoM-BH-1 suggest that black hole stars could account for at least some of these little red dots observed across the early universe.
