Expert: Courtney Seligman - 9/20/2010

Question
Has a star been observed falling into a black hole and disappearing?  

Answer
No.

We have seen ordinary black holes emitting high energy jets of material, which must be the result of gases swirling around the hole in an "accretion disk", gradually compressing and heating up, until they either fall into the hole or are ejected at the poles of the disk. But these do not represent a star being swallowed whole, because such black holes are only a few miles across, and stars are tens of thousand or even millions of miles across. Instead, they represent gases lost by the star being pulled toward the black hole, instead of just spreading out into space, and only a fraction of the material lost by the star actually ends up inside the black hole. In fact, usually the star simply ends up a little less massive, and dies a little sooner, but continues to orbit the hole (this sort of thing most commonly occurs in binary star systems, as described at Mass Transfer in Binary Star Systems (http://cseligman.com/text/stars/binary.htm)).

Now, quasars may represent something more like what you are asking about. They are believed to be caused by huge amounts of material falling into a supermassive black hole, and although they would mostly involve tearing material off the outside of a passing star, and leaving most of the star to go on its way, they could occasionally represent a star actually "running into" a black hole. But the nearest quasars are hundreds of millions and billions of light years away, so although we can tell that something interesting is going on, we have no way to see exactly what it is.

As a result, any images you may have seen of such things happening are strictly artists' impressions, meant to impress people, but not necessarily representing what is actually happening.