Physics: How does the torus form in this phenomenon?

Question

Click on the image to enlarge to better see the torus.
http://www.nasa.gov/centers/goddard/images/content/105143main_BH-longshot.jpg

Answer 1

It's a good question and the answer should be quite simple to grasp, but may be a little wordy to explain.
The torus you see forms for the same reason that all the planets and most of the other material in the solar system are in the same plane. If you could see our solar system from outside, it would appear to have a toroid shape too.
Even though star systems start with roughly a sperhical shape, once they start to collapse under gravity, they begin to rotate faster and faster due to the conservation of angular momentum (remember the image of the twirling ice skater who brings her hands and feet in and spins faster?)
All of the material that is above or below the equatorial plane of this rotation, does not have any force to act against the gravitational collapse. So it gets pulled down into the center of the whirling cloud.
On the other hand, the material that is in the equatorial plane, has linear momentum to act against the gravitational collapse (some people may try to call it "centrifugal force" but that is an arguement best left for another time). So the material going around the source of gravity along the equator of the cloud, is not pulled into the center and forms a disk or torus-like shape.
In the diagram you showed, the material coming off the companion star is just following the same basic pattern.
The companion star is rotating in the same plane, and this (plus the pull from the black hole) distorts the shape of the star just a little bit so that it is fatter near the equator. That part of the star is being pulled off in thin strips (like peeling an onion) and the gasses are already in that equatorial plane and so they just spiral around and around getting closer and closer until they are drawn in.

Answer 2

"An international team of scientists has found more evidence that massive black holes are surrounded by a doughnut-shaped gas cloud which, depending on our line of sight, blocks the view of the black hole in the center.

"Using two European Space Agency orbiting observatories, INTEGRAL and XMM-Newton, scientists looked "edge on" into this doughnut (called a torus by scientists) to see features never before revealed in such clarity. They could infer the doughnut structure and its distance from the black hole by virtue of light that was either reflected or completely absorbed. How the doughnut forms, however, remains a mystery.

""By peering right into the torus, we see the black hole phenomenon in a whole new light, or lack of light, as the case may be here," said Dr. Volker Beckmann of NASA Goddard Space Flight Center in Greenbelt, Md., the lead author on an upcoming article in The Astrophysical Journal. "This torus is not as dense as a Krispy Kreme doughnut, but it is far hotter (up to a thousand degrees) and loaded with many more calories.""
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I would have to say BLACK HOLE. Read the following articles...
they are a little technical.

Answer 3

I see a pulsar and a forming planet. I have a college astronomy book if you have a question. Is torus the 'planet in formation?' Yahoo messanger me. (projectjadeasylum6)