Supernovae and Black
is a supernova?
Merriam-Webster gives this as a definition for supernova: "the explosion of a star in which the star may reach a maximum intrinsic luminosity one billion times that of the sun." This means that at the end of a stars 'life' it may explode creating a light 1 x 109 times brighter than the star ever was. (m-w.com)
What causes a supernova?
Two main causes for a supernova are: The sun may stop fusing hydrogen into helium, this causes the gravity of the sun to pull in on itself making the size smaller, but the pressure greater. The other main cause would be that a white dwarf star, being near another star, begins to collect the gases from that larger nearer star, cause the dwarf to reach its Chandrasekhar limit, Space.com says. This causes the dwarf to begin fusing faster and in different places, ending in its destruction. (space.com)
*no stated author* [www.space.com/supernovas]
What is a black hole?
Merriam-Webster gives this as a definition for a black hole: "a celestial object that has a gravitational field so strong that light cannot escape it." This means that when a black hole is created, it begins to pull in anything within its gravity and holds everything, including light, inside. (m-w.com)
What causes a black hole?
Black holes are created at the end of a stars life. Black holes are the end points of supernovae. At the end of a supernovae, pieces of the star may be left behind. These pieces implode (close in on themselves) and the gravitational pull grows. The gravitational pulls grows because the 'remnants' after the implosion have "no mass and infinite density" as an author for NASA states.
How big are they?
One of the longest lasting known black hole is a white dwarf known as Cygnus X-1. The black hole is 3000 kilometers (or approx. 1864 miles) in diameter. We know this by the amount of flickering of x-rays that come off the hole.(nasa.gov)