Astronomers discover cosmic monster that is neither star nor black hole

James Webb Space Telescope observations reveal a mysterious object from the early universe that may be a black hole wrapped in a vast, star-like envelope of gas

Astronomers have found something the textbooks don't have a name for: an object that looks like a star, burns like nothing in nature should, and may be powered by a black hole wearing a star's disguise.

 

Peering back to when the universe was only a few hundred million years old, astronomers using Nasa's James Webb Space Telescope have spotted a blazing red pinprick of light that doesn't fit any known category of cosmic object. They are calling it a "black hole star".

 

At first glance, the object, named MoM-BH*-1, looks like an enormous star, roughly the size of our solar system. The object is pumping out roughly 100 billion times more energy than nuclear fusion could ever produce in a star of that size. The astronomers, therefore, believe its power source is not nuclear fusion, as in normal stars, but a black hole buried inside a huge cloud of dense hydrogen gas.

 

Lead author of the study Rohan Naidu, a Nasa Hubble fellow and Pappalardo fellow at MIT’s Kavli Institute for Astrophysics and Space Research, said the team’s understanding of the object is evolving rapidly. 

 

"We think there is a central black hole that is 100,000 times as massive as the sun. Around this black hole, there would be this very extended envelope of gas that looks like a star the size of the solar system. It's huge," he said in a blog published by Massachusetts Institute of Technology (MIT).

 

The discovery may finally explain one of JWST's most persistent riddles: the so-called "little red dots" that keep turning up scattered across images of the infant universe, defying easy classification.

 

How a black hole can look like a star

 

The proposed object is essentially a black hole wrapped in a vast envelope of gas.

 

As material falls towards the black hole, it releases enormous amounts of energy. The surrounding hydrogen absorbs and re-emits that energy, making the entire structure appear from afar like a giant, glowing star.

 

According to MIT, this could explain why the object has an unusual red colour and a distinctive pattern in its light. The researchers found that the signal could not be adequately explained by ordinary stars or dust alone, while models involving a black hole surrounded by dense hydrogen reproduced the observations.

 

Astronomers have struggled to explain these compact, unusually bright objects. If the black hole-star model is correct, many of those red dots could be young black holes hidden inside dense clouds of gas.

 

Why the discovery matters

 

The finding could also shed light on how supermassive black holes grew so quickly in the young universe.

 

Black holes weighing millions or even billions of times the mass of the Sun have been observed surprisingly early in cosmic history. Conventional models have difficulty explaining how they could grow so massive in such a short period.

 

A black hole surrounded by a huge supply of gas could provide a rapid-growth phase: the black hole would continuously feed on the surrounding material while its gaseous envelope makes it appear like a star.

 

The researchers leading the study stress that MoM-BH*-1 is a candidate for this new type of object, rather than a definitively established new class.

 

If confirmed by further observations, the object could give astronomers a new window into the period when the universe's first galaxies and supermassive black holes were taking shape.