what is the mass of black whole?
They vary. Limits on the mass of a black hole have a miniumu mass of 2E-8kg and a maximum mass near 2E40kg
The essence of a black hole is NOT its mass, but its density.
The sum of the masses of the parts of the whole.
If you mean black HOLE, it can have any value if the density is high enough. Stephen Hawking has postulated "mini black holes" but none have been found so far. Black holes formed by the supernova explosions of stars have masses of several suns or more. Black holes at the centers of galaxies have ben found to have masses of millions suns.
http://www.space.com/scienceastronomy/080903-our-black-hole.html
To determine the mass of a black hole, you would typically employ indirect methods, as directly measuring the mass of a black hole is scientifically challenging. However, scientists make use of the behavior of objects and light near a black hole to estimate its mass. Here's how they do it:
1. Stellar Dynamics: One method involves observing the motion of stars in a binary system, where a companion star orbits a black hole. By analyzing the orbital parameters and the speed at which the stars move, scientists can calculate the mass of the invisible black hole.
2. Gas Accretion: When a black hole is actively feeding on nearby gas and dust, it forms an accretion disk. Scientists study the properties of this disk, including the temperature and luminosity, which provide information about the black hole's mass.
3. Gravitational Waves: Another method is to detect gravitational waves produced by the merging of two black holes. By analyzing these waves using specialized detectors, scientists can estimate the masses of the black holes involved.
It's important to note that while these methods are reliable, they still involve some degree of uncertainty due to the limitations of our current technology and understanding of black holes.