It seems that every illustration of a black hole pulling matter off a star looks like this one from the Chandra X-ray Observatory website.
Or this one from Nature - Two black holes found in a star cluster (Pay walled)
Two things bother me about this kind of illustration.
First the stream of matter being sucked off the star looks like a taffy pull. On a galactic scale, I could understand this. Over time, an unstructured elliptical galaxy develops bars and spiral arms from self gravitation.
But here matter is pulled off by tidal forces. At the nearest area of the stars surface, the attraction from the black hole exceeds the attraction from the star. Once separated from the star, this matter should follow an orbit around the black hole, not fall straight in. Being hot gas, atoms have a range of speeds and directions. Some would head toward the black hole. I would not expect self gravitation to pull it together like this. The solar wind shows no signs of this kind of organization. If anything, I would expect the accretion disk to extend to the star.
Second, the accretion disk is flat like Saturn's rings. I can understand how rotating dust and gas would flatten itself in a protoplanetary system or around a planet. But as it falls in, it is compressed and heated to millions of degrees. It isn't like a near vacuum protoplanet. Pressure is high. Would it flatten under these circumstances, or would pressure push gas above and below the orbital plane?
It seems that these illustrations must be an artist's vision. But they appear in scientific contexts. I rarely see anything different. So is it realistic? If so, what is the explanation?
