Black holes have been detected in binary star systems. These black holes are usu
ID: 1837905 • Letter: B
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Black holes have been detected in binary star systems. These black holes are usually found by observing the sky in X-rays. When material from the partner star is pulled off the star and begins to rapidly spiral into the black hole, the collisions between atoms is extremely violent. This allows them to radiate light from the accretion disk of material. What is found from further observations is that material that is farther from the black hole, and which has less kinetic energy, radiates in the optical and ultraviolet wavelengths. As the material gets close to the event horizon, it is moving very fast and collisions produce X-rays. When the material is so close to the event horizon that it is about to fall in, the radiation start to move back toward ultraviolet and optical wavelengths again. Why does this happen? Colored light can be mixed to form new colors. For instance, mixing red and green light gives you yellow light. The black hole has extremely black, long wavelength light, while the accretion disk is extremely white, short wavelength light. Near the event horizon the two colors mix and you get light that has an in between wavelength. This makes the light near the event horizon appear to have longer wavelengths. As you get nearer to the Event Horizon there is more and more material packed closely together. This high density allows many more collisions which produce light. Very close to the Event Horizon, material begins to fall in to the black hole. This decreases the density in the accretion disk and the fewer coupons cause the light to be less energetic. Near the Event Horizon clocks begin to run very slow. The material spiraling in is moving at enormous speeds and the collisions should produce even shorter wavelength light than X-Rays. But since the clocks are running slow, relative to our clocks, the vibration of the particles appear to stow down near the Event Horizon. The slow oscillations set off during collisions then produces longer wavelength light. The large gravitational field, near the Event Horizon, pulls very hard on the light trying to escape. The effect is like a slinky (or long spring) which is being held at one end. Think of the coils as the wavelength of the light. When the slinky is compressed the coils are close (short wavelength), but if someone walks away from you holding the other end, while the end you are holding is not moving, the slinky coils will expand, as the person walks away. Light trying to leave the black hole is held at one end by gravity and stretches out as it tries to escape. This is gravitational red-shift.Explanation / Answer
I think it is the last option which is correct.
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