How is it that when a black hole and a star collide, that some gas escapes from the collision?

Question

And how is it that gamma radiation also escapes from the collision? And why is the collision so bright if light can not escape a black hole?

Answer 1

I'm not xactly sure but I'm glad I don't have to smell it.

Answer 2

If either the star or the black hole, or both, are spinning, then some material may attain an orbital velocity that prevents it from falling in past the event horizon. Gamma radiation can be emitted as in-falling material reaches high speeds, creating heat, light, and energy as it falls inward.

Answer 3

Some of the gas might be thrown out before it crosses the event horizon (point where nothing can escape) and ends up being thrown out into space. Gamma radiation can escape because its not a particle but truthfully I don't completely know. Hope this helps a little.

Answer 4

In any collision of things that big, there are always bits and pieces at the edge of the collision.  These bang into each other in random ways and with multiple hits, causing debris to fly in all directions.  "Random" does not mean, however, uniformly in all directions -- some directions get more stuff than others.

The bits and pieces for a star & BH are the dust and gas in the star and around the BH.   The collision is so violent, that some of these hit each other at *very* high speeds, causing X-ray and even gamma radiation.  

The brightness comes from these collisions and from flares on the star, all before stuff falls into the BH.  As a matter of fact, most of the star stuff is pushed away from the BH, by the energy of the 5% or so that does fall in.

Answer 5

Everything depends on the speed and angle that material moves towards a black hole. Almost everything caught by a black hole's gravitational attraction is *first* accelerated to near the speed of light, including stars which are literally shredded into little more than molecules of gas. If the angle of approach of some material is oblique enough and the velocity high enough, it can "slingshot" back into space.

The gamma radiation you ask about is generated by the internal friction of all the material being drawn towards the black hole and can escape back into space for the same reasons as outlined above.