Stellar BLack Holes #1

[Shallara Navor Hevoda 0]

The strange forces of electron and pressure support dying lightweight stars and some heavyweight stars agenst gravity. The strangest case of all occures at the death of the most massive stars, which comtained much more then 8 and up to about 60 sollar masses when they were on the main sequence. After these stars undergo supernova explosions, some mayretian cores of over 2 or 3 sollar masses. Nothing in the known universe is strong enooough to hold up the remaining mass agenst the force of gravity. The remaining mass collapses, and continues to colaps forever.

The result is a black hole, in which the matter disappears from contact with the rest of the universe. Later, we shall discuss the formation of black holes in processes other than those that result from the colaps of a star.

 

The formation of a stellar black hole

Astronomers had long assumed that the most massive stars would somehow lose enough mass to wind up as White Dwarfs. When the discovery of Pulsars ended this prejudice, it seemed more reasonable that black holes could exist. If more then 2 or 3 times the mas of the Sun -- two or three "sollar massas" -- remains after the Supernova explosion, the star colapses through the neutron star stage. At present we know of no force that can stop the colapse.

We may then ask what happens to a 5- or 10- or 50-sollar-mass staras it collapses, if it retains more then 2 or 3 sollar masses. It must keep colapsing getting denser and denser. We know that Einstien's generall theory of Relativity predicts that a strong gravitationall fieldwill redshift and appear to bend radiation. As the mas contracts and the star's surface gravity increases, radiation is continuously redshifted more and more. Also, radiationleaving the star other then perpendiculary to the surface is bent more and more. Eventually, when the mass has been compressed to a certain size, radiation from the star can no longer escape into space. The star has withdrawn from our observable Universe, in that we can no longer recieve radiation from it. We say that the star has become a "Black Hole"

Why do we call them black holes? We think of a black surface as a surface that reflects none of the light that hits it. Similarly, any radiation that hits a black hole continues into it's interiorand is not reflected. In this sense, the object is perfectly black.

[Dumbass 0]

Yeah, and what is the difference between a super nova vs one that is merely mediocre?

[DaryusZaphodDracal 0]

Yeah, and what is the difference between a super nova vs one that is merely mediocre?

The '69 was a super Nova, the '74 a mediocre Nova, and the '77 a peice of crap Nova. (Chevy that is) ;)

[Shallara Navor Hevoda 0]

For massive stars, the core contracts as the outer layers expand. The core reaches 100 million degrees, and the tripple-alpha process begins to transform helium into carbon.By the time the helium is exhausted, the outer layers have evaporated evenfurther. The star has become so bright that we call it a "Red Supergiant". Betelgeuse the star that makes the shoulder of Orion, is the best known example.

The carbon core of a supergiant contracts, heats up, and begins fusing into still heavier elements. Each stage of fusion gives off energy. Eventually, even iron builds up. The iron core is sourounded by layers of elements, it takes up it takes up energy instead of givving it off. No new enerdy is released to make enough pressure to hold up the star agenst the forces of gravity pulling it in. Within seconds, the star collapses. It rebounds and bursts outwardl with amazing brightness. It has become a Supernova. Shock waves - like sonic booms - that result cause heavy elements to form and then throw off the outer layers.

 

 

Any outher questions? ;)

[Dumbass 0]

Actually, Daryus's answer was easier to understand. ;)