Last year, when scientists presented the first photo of a black hole in history, it was hailed as an extraordinary breakthrough.
Well, now they have re-evaluated some of the image data acquired in the years before the historical snapshot was obtained.
It gives us some new perspectives, called M87*, which has a mass of 6.5 billion suns.
One insight is the realization that the brightness of black holes flickers over time.
This may be the result of M87* crushing and consuming nearby material captured by its gravitational force.
Matter heated to billions of degrees will bend under the action of a strong magnetic field. In this way, the brightness area seen in the gas ring surrounding the black hole seems to oscillate.
Dr. Maciek Wielgus, an astronomer at Harvard University in the United States, explained: “What we see is the flow of matter rotating around the event horizon and eventually rushing into the event line of sight, but the plasma flow of this matter is very turbulent.”
He told the BBC: “We expect this kind of turbulence. There will be magnetic rotation instability in this kind of turbulence. For this reason, there is a certain randomness (randomness of behavior); the brightness spots seem to be in different positions. Formed.”
The Event Horizon Telescope (EHT) captured historical images of M87* released in April 2019.
This is a “virtual observatory”. It connects a series of eight radio receivers-from Antarctica to Hawaii to America and Europe-to simulate the resolution you get with an earth-sized telescope.
Astronomers describe the resolution obtained as 42 microseconds. For laymen, this is a keen vision, which is equivalent to “be able to watch billiards or snooker on the moon, and be able to follow the movement of the ball,” said Dr. Verges.
This is what you need for a detailed view of an object (even an object as large as M87*), which is 53 million light years away (about 500 million billion kilometers).
Last year, the images we saw on newspapers, websites and TV screens were bagel-like features-an accretion disk, which is a circle of overheated, excited gas rotating around a dark central area where a black hole is expected to exist .
The picture comes from the value of the linked EHT array during a week of joint observation-followed by a long period of computer processing and analysis.
But, of course, by then, many years of preparation, trial and error, and fewer radio receivers than in the final EHT configuration have been carried out.
Dr. Wielgus and his colleagues have now reviewed and traced all the practical data back to 2009, and published a paper in the Astrophysical Journal.
What is a black hole?
A black hole is a spatial region where matter itself collapses
Gravity is so strong that nothing, not even light, can escape
The explosive death of certain large stars will create black holes
But some are really huge, billions of times the mass of our sun
How these monsters found in the center of the galaxy formed is unclear
Detect black holes in the way they affect the surrounding environment
What they did was basically re-evaluate the archived material based on everything they learned when producing the final 2019 image.
They cannot see the complete image from the old data, but they can use the model to extract details to confirm certain features and behaviors in M87*, which should have appeared in earlier years.
“There is no older data cycle better than one data cycle. [for the 2019 image]”, said Professor Anton Zeng Suss, director of the Max Planck Institute for Radio Astronomy in Germany and the founding chairman of EHT.
“But all of this can be viewed, knowing that there is an underlying ring structure there. So if you restrict the starting conditions for viewing this data, then the ring structure is actually obvious in all these sessions. 2009. Therefore, the significance is that we have confirmed  Get results by looking at older data. “
Identifying the changing position of brightness in the M87* accretion disk is one of the results of this research.
The other is to simply confirm whether the diameter of this ring structure is constant, thereby determining the diameter of the black hole itself, or more precisely its event range: the speed required to escape gravity even exceeds that of light.
For M87*, the width of this “surface” is approximately 40 billion kilometers. Think of a region of space about twice the size of our solar system.
The other thing this research does is to give us an understanding of the future capabilities of EHT.
Logically, if you run data for many years together, you should be able to make movies about activities near the black hole.
But this will require more radio receivers to be incorporated into the EHT array and extend the observation period.
Currently, EHT only works for a few days in late March (early April) each year, because this is the time when the weather conditions of all different radio stations around the world are usually good during the year.
Jonathan.Amos-INTERNET@bbc.co.uk, then follow me on Twitter: @BBCAmos