Based on new observations, an international team of researchers estimate the black hole is 21 times the mass of our sun and spinning faster than any other known black hole.

The recalculated weight is causing scientists to rethink how bright stars that turn into black holes evolve, and how fast they shed their skins before they die.

The mass of a black hole depends on the properties of its parent star, such as the star's mass and its metallicity (how much of it is made up of elements heavier than helium).

Bigger stars rich in heavy elements shed their mass faster than smaller stars with less metallicity, scientists think.

But to make a black hole this heavy and rotating so quickly, we need to dial down the amount of mass that bright stars lose during their lifetimes," study co-author Ilya Mandel, an astrophysicist from Australia's Monash University said in a statement.

In addition, Cygnus X-1's black hole is slowly devouring its bright blue companion star by sucking in that star's outer layers, forming a bright disk rotating around the black hole.

Over a period of six days, they followed the black hole's full orbit around its companion star and determined how much the black hole shifted in space. .

And given the orbital period of the black hole, they were able to give a new estimate for the black hole's mass — a whopping 21 solar masses.

"Using the updated measurements for the black hole's mass and its distance away from Earth, we were able to confirm that Cygnus X-1 is spinning incredibly quickly — very close to the speed of light and faster than any other black hole found to date," study co-author Lijun Gou, a researcher at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), said in the statement.