Just like White Dwarfs are the evolutionary endpoint for a low mass to medium size star, black holes are one of the two possible fates of a massive star. A massive star is a star that which mass surpass 8M (solar masses). Black holes are, despite popular belief, not made up of highly compact matter. Black holes are in fact matter that no longer exist.
What defines a black hole is an area or region of space that
which gravitational field is too strong for any matter,
radiation or even the fastest moving particles to escape it.
That is when the matter enter the Schwarzschild radius or, as
it is also called, the gravitational radius. The formula for
the Schwarzschild radius is Rg = (2GM)/c^2, where g = the
universal gravitational constant, c = the speed of light and
M = the mass of an object.
The reason that black holes are black are because not even
light can escape the gravitational pull of a black holethe
light gets pulled back by gravity. The reason that black holes
are completely empty is because the system, or object, that
collapsed from it is shriveled away to nothing.
Surrounding the black hole there is a thing called the
‘event horizon’ which is the threshold around it where the
speed of light is surpassed by the escape velocity.
The density of a black hole differs depending on how large it
is and how you define its size. In the center of a black hole,
the density is infinite. To calculate the density of a black hole
you can youse the formula mentioned earlier, the Schwarzschild
radius (Rg = 2GM/c2). To do that you would divide the mass by the
volume, confined within the Schwarzschild radius. That is assuming
you know the radius of the sphere, which is required for an
accurate calculation. To calculate the radius of the sphere you
can use the formula 3x10^5 cm x (M / Msun) then we get 3x10^5 cm
x 3.7 × 10^6 = 1.125 × 10^12. To calculate the radius of the sphere
you can use the formula 3x10^5 cm x (M / Msun) then we get 3x10^5 cm
x 3.7 × 10^6 = 1.125 × 10^12.
To then calculate the mass of the sphere you multiply 3.7 by 10^6
Msun × 1.98892 × 10^33 g/Msun = 7.359 × 10^39 g.
To do this quicker you can use the formula (1,8*10^16 g/cm^3)
*(1/ 3.7*10^16)^2 =1.31^10^3 g/cc
alt. (1.8*10^16 g/cm^3)*(Msun/M)^2
A stellar black hole is created when a massive star reaches the end of its life cycle, when the star implodes and collapses in upon itself. This also generates a supernova. Black holes are believed by scientists, to have formed in the beginning of our universe’s existence.
The reason black holes genereally spin is believed to be because the massive stars they originated from were spinning too. Also because the matter that get consume whirled in spirals before it were sucked in. The rotation of the black holes are believed to be capable of going faster than 90% of the speed of light, according to recent findings.
Actually, there is a phenomenon called Lense-thirring effect or frame dragging. This occurs when a spinning black hole causes the fabric of spacetime to also rotate along with the black hole. This is a phenomenon that does not exclusively affect black holes but also other bodies like earth.
Black holes are invisible to the human eye due to the strong gravity pull, swallowing all the light that reaches it. What we can see are how the surroundings are affected by the strong force that it’s gravity has. When a black hole and a star are close to each other, another kind of light is created. Neither can this light be seen with human eyes but scientists can use telescopes and satellites to observe it. This type of light is called high-energy light.