Here is the main equation for a black hole. - 75 Mby 53 Problems A revised and expanded introduction to the basic properties of black holes using elementary algebra and geometry. R s 2 G M c 2 295 M M S u n k m displaystyle r_ mathrm s frac 2GM c 2approx 295 frac M M_ mathrm Sun mathrm km.
Black hole mass dimensionless spin parameter gravitational constant speed of light angular momentum speed of sound proton mass Thomson scattering cross section radiative efficiency reduced Plancks constant Boltzmanns constant.
Here G is the gravitational constant and c is the speed of light.